diff --git a/DeepSqueak.fig b/DeepSqueak.fig
index 3e465e84..5d64db3a 100644
Binary files a/DeepSqueak.fig and b/DeepSqueak.fig differ
diff --git a/DeepSqueak.m b/DeepSqueak.m
index 9d6fcb8e..54ff44bd 100644
--- a/DeepSqueak.m
+++ b/DeepSqueak.m
@@ -282,6 +282,46 @@ function PreviousCall_Callback(hObject, eventdata, handles)
 update_fig(hObject, eventdata, handles);
 
 
+% --- Executes on button press in NextFile.
+function NextFile_Callback(hObject, eventdata, handles)
+numfiles = length(handles.detectionfiles);
+%Make sure we actually have an active Detections folder
+if numfiles > 0
+    handles.current_file_id = get(handles.popupmenuDetectionFiles,'Value');
+    % Check for a next file
+    if handles.current_file_id < numfiles
+        % If confirmed possible, increment to next file
+        handles.current_file_id = handles.current_file_id + 1;
+        filename = fullfile(handles.detectionfiles(handles.current_file_id).folder, handles.detectionfiles(handles.current_file_id).name);
+        % filename argument bypasses the behavior of pressing the LoadCalls button
+        cancelled = loadcalls_Callback(hObject, eventdata, handles, 'filename', filename);
+        % Make sure the drop-down matches what's happening internally
+        if ~cancelled
+            handles.popupmenuDetectionFiles.Value = handles.current_file_id;
+        end
+    end
+end
+
+% --- Executes on button press in PrevFile.
+function PrevFile_Callback(hObject, eventdata, handles)
+numfiles = length(handles.detectionfiles);
+%Make sure we actually have an active Detections folder
+if numfiles > 0
+    handles.current_file_id = get(handles.popupmenuDetectionFiles,'Value');
+    % Check for a previous file
+    if handles.current_file_id > 1
+        % If confirmed possible, decrement file
+        handles.current_file_id = handles.current_file_id - 1;
+        filename = fullfile(handles.detectionfiles(handles.current_file_id).folder, handles.detectionfiles(handles.current_file_id).name);
+        % filename argument bypasses the behavior of pressing the LoadCalls button
+        cancelled = loadcalls_Callback(hObject, eventdata, handles, 'filename', filename);
+        % Make sure the drop-down matches what's happening internally
+        if ~cancelled
+            handles.popupmenuDetectionFiles.Value = handles.current_file_id;
+        end
+    end
+end
+
 % --- Executes on selection change in Networks Folder Pop up.
 function neuralnetworkspopup_Callback(hObject, eventdata, handles)
 guidata(hObject, handles);
@@ -494,11 +534,11 @@ function export_raven_Callback(hObject, eventdata, handles)
     end
 end
 a  = cell2table(raventable);
-handles.current_file_id = get(handles.popupmenuDetectionFiles,'Value');
-current_detection_file = handles.detectionfiles(handles.current_file_id).name;
-ravenname=[strtok(current_detection_file,'.') '_Raven.txt'];
-[FileName,PathName] = uiputfile(ravenname,'Save Raven Truth Table (.txt)');
-writetable(a,[PathName FileName],'delimiter','\t','WriteVariableNames',false);
+% Get the name of the output file and save the table
+[PathName, FileName, ~] = fileparts(handles.current_detection_file);
+ravenName = fullfile(PathName, [FileName '_Raven.txt']);
+[FileName,PathName] = uiputfile(ravenName,'Save Raven Truth Table (.txt)');
+writetable(a, fullfile(PathName, FileName), 'delimiter', '\t', 'WriteVariableNames', false);
 guidata(hObject, handles);
 
 % --------------------------------------------------------------------
@@ -697,12 +737,22 @@ function backwardButton_Callback(hObject, eventdata, handles)
 jumps = floor(handles.data.focusCenter / handles.data.settings.pageSize);
 handles.data.windowposition = jumps*handles.data.settings.pageSize;
 
-calls_within_window = find(handles.data.calls.Box(:,1) < handles.data.windowposition + handles.data.settings.pageSize, 1, 'last');
-if ~isempty(calls_within_window)
-    handles.data.currentcall = calls_within_window;
-    handles.data.current_call_valid = true;
+% if we can't page because we're at the beg of the file, make the first call
+% the current call
+if jumps == 0
+    if ~isempty(handles.data.calls)
+        handles.data.currentcall = 1;
+        handles.data.current_call_valid = true;
+    end
+% Otherwise make the last call in the new page window the current call
+% (will not necessarily be in focusWindow)
+else
+    calls_within_window = find(handles.data.calls.Box(:,1) < handles.data.windowposition + handles.data.settings.pageSize, 1, 'last');
+    if ~isempty(calls_within_window)
+        handles.data.currentcall = calls_within_window;
+        handles.data.current_call_valid = true;
+    end
 end
-
 update_fig(hObject, eventdata, handles);
 
 
@@ -718,10 +768,21 @@ function forwardButton_Callback(hObject, eventdata, handles)
 % handles.data.focusCenter = max(0, handles.data.windowposition - handles.data.settings.focus_window_size ./ 2);
 % get_closest_call_to_focus(hObject, eventdata, handles);
 
-calls_within_window = find(handles.data.calls.Box(:,1) > handles.data.windowposition, 1);
-if ~isempty(calls_within_window)
-    handles.data.currentcall = calls_within_window;
-    handles.data.current_call_valid = true;
+% if we can't page because we're at the end of the file, make the last call
+% the current call
+if jumps == 0
+    if ~isempty(handles.data.calls)
+        handles.data.currentcall = height(handles.data.calls);
+        handles.data.current_call_valid = true;
+    end
+% Otherwise make the first call in the new page window the current call
+% (will not necessarily be in focusWindow)
+else
+    calls_within_window = find(handles.data.calls.Box(:,1) > handles.data.windowposition, 1);
+    if ~isempty(calls_within_window)
+        handles.data.currentcall = calls_within_window;
+        handles.data.current_call_valid = true;
+    end
 end
 
 update_fig(hObject, eventdata, handles);
@@ -820,30 +881,32 @@ function topRightButton_Callback(hObject, eventdata, handles)
 
 % --- Executes on button press in loadAudioFile.
 function loadAudioFile_Callback(hObject, eventdata, handles)
+cancelled = checkForUnsavedChanges(hObject, eventdata, handles);
+if cancelled
+    return
+end
+
 h = waitbar(0,'Loading Audio Please wait...');
 update_folders(hObject, eventdata, handles);
 handles = guidata(hObject);
 
-if nargin == 3 % if "Load Calls" button pressed
-    if isempty(handles.audiofiles)
-        close(h);
-        errordlg(['No valid audio files in current audio folder. Select a folder containing audio with '...
-            '"File -> Select Audio Folder", then choose the desired file in the "Audio Files" dropdown box.'])
-        return
-    end
-    handles.current_file_id = get(handles.AudioFilespopup,'Value');
-    handles.current_audio_file = handles.audiofiles(handles.current_file_id).name;
+if isempty(handles.audiofiles)
+    close(h);
+    errordlg(['No valid audio files in current audio folder. Select a folder containing audio with '...
+        '"File -> Select Audio Folder", then choose the desired file in the "Audio Files" dropdown box.'])
+    return
 end
 
-handles.data.audiodata = audioinfo(fullfile(handles.data.settings.audiofolder,handles.current_audio_file));
+current_file_id = get(handles.AudioFilespopup,'Value');
+handles.data.audiodata = audioinfo(fullfile(handles.data.settings.audiofolder, handles.audiofiles(current_file_id).name));
+
+% Create a filename for the new detection file
+[~, filename, ~] = fileparts(handles.data.audiodata.Filename);
+handles.current_detection_file = fullfile(handles.data.settings.detectionfolder, [filename '.mat']);
+
+% Initialize the empty calls variable
+handles.data.calls = table(zeros(0,4),[],[],[], 'VariableNames', {'Box', 'Score', 'Type', 'Accept'});
 
-Calls = table(zeros(0,4),[],[],[], 'VariableNames', {'Box', 'Score', 'Type', 'Accept'});
-% Calls.Box = [0 0 1 1];
-% Calls.Score = 0;
-% Calls.Type = categorical({'NA'});
-% Calls.Power = 1;
-% Calls.Accept = false;
-handles.data.calls = Calls;
 % Position of the focus window
 handles.data.focusCenter = handles.data.settings.focus_window_size ./ 2;
 initialize_display(hObject, eventdata, handles);
diff --git a/Functions/Batch_Reject_by_Threshold_Callback.m b/Functions/Batch_Reject_by_Threshold_Callback.m
index 127d11e6..142103b1 100644
--- a/Functions/Batch_Reject_by_Threshold_Callback.m
+++ b/Functions/Batch_Reject_by_Threshold_Callback.m
@@ -157,7 +157,7 @@ function Batch_Reject_by_Threshold_Callback(hObject, eventdata, handles)
 end
 close(h);
 
-%update the display
-if isfield(handles,'current_detection_file') && any(ismember(handles.detectionfilesnames(selections),handles.current_detection_file))
-    loadcalls_Callback(hObject, eventdata, handles, handles.current_file_id)
+% reload the file if the currently loaded file was modified
+if isfield(handles,'current_detection_file') && any(ismember(fullfile(handles.detectionfiles(1).folder,handles.detectionfilesnames(selections)),handles.current_detection_file))
+    loadcalls_Callback(hObject, eventdata, handles, 'filename', handles.current_detection_file, 'checkForChanges', false)
 end
diff --git a/Functions/checkForUnsavedChanges.m b/Functions/checkForUnsavedChanges.m
new file mode 100644
index 00000000..179c03f0
--- /dev/null
+++ b/Functions/checkForUnsavedChanges.m
@@ -0,0 +1,28 @@
+function cancelled = checkForUnsavedChanges(hObject, eventdata, handles)
+%% Check if the current file has been modified. If it has, prompt the user to save it
+% cancelled = false if the user pressed "Yes" or "No"
+% cancelled = true if user pressed "Cancel"
+
+cancelled = false;
+if ~isempty(handles.data.calls)
+    if isfile(handles.current_detection_file)
+        oldCalls = loadCallfile(handles.current_detection_file, handles);
+        % Check if the "box", "type", and "accept" fields in the currently loaded
+        % file are the same as the old file. Do this instead of comparing
+        % all fields because previous versions of DS had additional
+        % variables, so this prevents compatibility errors.
+        % isequal doesn't work when categorical variables have undefined
+        % entries, so test them seperately.
+        if ~isequal(handles.data.calls(:,{'Box', 'Accept'}), oldCalls(:,{'Box', 'Accept'})) || ~isequal(cellstr(handles.data.calls.Type), cellstr(oldCalls.Type))
+            response = questdlg('Calls have been modified, save changes?', 'Save changes', 'Yes', 'No', 'Cancel', 'Yes');
+            switch response
+                case 'Yes'
+                    cancelled = savesession_Callback(hObject, eventdata, handles);
+                case 'No'
+                    cancelled = false;
+                case 'Cancel'
+                    cancelled = true;
+            end
+        end
+    end
+end
\ No newline at end of file
diff --git a/Functions/loadCallfile.m b/Functions/loadCallfile.m
index 91815ff6..e1458f49 100644
--- a/Functions/loadCallfile.m
+++ b/Functions/loadCallfile.m
@@ -9,6 +9,10 @@
 %% Unpack the data
 if isfield(data, 'Calls')
     Calls = data.Calls;
+    % Back Compatability for Files with Power in The Detection File.
+    if ismember('Power',Calls.Properties.VariableNames)
+        Calls = removevars(Calls, 'Power');
+    end
 elseif nargout < 3 % If ClusteringData is requested, we don't need Calls
     error('This doesn''t appear to be a detection file!')
 end
diff --git a/Functions/loadcalls_Callback.m b/Functions/loadcalls_Callback.m
index 4c3e626e..7b6b8575 100644
--- a/Functions/loadcalls_Callback.m
+++ b/Functions/loadcalls_Callback.m
@@ -1,9 +1,29 @@
 % --- Executes on button press in LOAD CALLS.
-function loadcalls_Callback(hObject, eventdata, handles, reload_current_file)
+function cancelled = loadcalls_Callback(hObject, eventdata, handles, varargin)
+% Inputs:
+%     filename - full path of the file to load. If filename is not given, load the file selected in the dropdown menu.
+%     checkForChanges - If true, check if the current session matches the saved file
+% Outputs
+%     cancelled - true if the user pressed cancel when prompted to save changes, else false
+
+p = inputParser;
+addParameter(p, 'filename', []);
+addParameter(p, 'checkForChanges', true);
+parse(p, varargin{:});
+
+
+cancelled = false; 
+if p.Results.checkForChanges
+    cancelled = checkForUnsavedChanges(hObject, eventdata, handles);
+end
+if cancelled
+    return
+end
+
 h = waitbar(0,'Loading Calls Please wait...');
 update_folders(hObject, eventdata, handles);
 handles = guidata(hObject);
-if nargin == 3 % if "Load Calls" button pressed, load the selected file, else reload the current file
+if isempty(p.Results.filename) % if "Load Calls" button pressed, load the selected file, else reload the current file
     if isempty(handles.detectionfiles)
         close(h);
         errordlg(['No valid detection files in current folder. Select a folder containing detection files with '...
@@ -11,17 +31,14 @@ function loadcalls_Callback(hObject, eventdata, handles, reload_current_file)
         return
     end
     handles.current_file_id = get(handles.popupmenuDetectionFiles,'Value');
-    handles.current_detection_file = handles.detectionfiles(handles.current_file_id).name;
+    handles.current_detection_file = fullfile(handles.detectionfiles(handles.current_file_id).folder,  handles.detectionfiles(handles.current_file_id).name);
+elseif isfile(p.Results.filename)
+    handles.current_detection_file = p.Results.filename;
 end
 
 handles.data.calls = [];
 handles.data.audiodata = [];
-[handles.data.calls, handles.data.audiodata] = loadCallfile(fullfile(handles.detectionfiles(handles.current_file_id).folder,  handles.current_detection_file), handles);
-
-%% Back Compatability for Files with Power in The Detection File.
-if ismember('Power',handles.data.calls.Properties.VariableNames)
-   handles.data.calls = removevars(handles.data.calls,'Power');
-end
+[handles.data.calls, handles.data.audiodata] = loadCallfile(handles.current_detection_file, handles);
 
 % Position of the focus window to the first call in the file
 handles.data.focusCenter = handles.data.calls.Box(1,1) + handles.data.calls.Box(1,3)/2;
diff --git a/Functions/savesession_Callback.m b/Functions/savesession_Callback.m
index 552414a6..f4256adc 100644
--- a/Functions/savesession_Callback.m
+++ b/Functions/savesession_Callback.m
@@ -1,28 +1,22 @@
-function savesession_Callback(hObject, eventdata, handles)
+function cancelled = savesession_Callback(hObject, eventdata, handles)
+% cancelled = false if saved successfully, else success = true
+cancelled = false;
 
-handles.v_det = get(handles. popupmenuDetectionFiles,'Value');
-if isfield(handles,'current_detection_file')
-    handles.SaveFile = handles.detectionfiles(handles.v_det).name;
-    handles.SaveFile = handles.current_detection_file;
-else
-    handles.SaveFile = [strtok(handles.audiofiles(handles.v_det).name,'.') '.mat'];
+if isempty(handles.data.calls)
+    disp('Can''t save session, no calls are loaded')
+    return
 end
 
-% temp = handles.data.audiodata.samples;
-% handles.data.audiodata.samples = [];
-guidata(hObject, handles);
-
 Calls = handles.data.calls;
 audiodata = handles.data.audiodata;
-[FileName, PathName] = uiputfile(fullfile(handles.data.settings.detectionfolder, handles.SaveFile), 'Save Session (.mat)');
+[FileName, PathName] = uiputfile(handles.current_detection_file, 'Save Session (.mat)');
 if FileName == 0
+    cancelled = true;
     return
 end
-h = waitbar(0.5, 'saving');
 
-
-save(fullfile(PathName, FileName), 'Calls','audiodata', '-v7.3');
-% handles.data.audiodata.samples = temp;
+h = waitbar(0.5, 'saving');
+save(fullfile(PathName, FileName), 'Calls','audiodata', '-append');
 update_folders(hObject, eventdata, handles);
-guidata(hObject, handles);
 close(h);
+
diff --git a/Functions/set_static_box_height_Callback.m b/Functions/set_static_box_height_Callback.m
index 3bfaf870..3076f0ba 100644
--- a/Functions/set_static_box_height_Callback.m
+++ b/Functions/set_static_box_height_Callback.m
@@ -54,6 +54,6 @@ function set_static_box_height_Callback(hObject, eventdata, handles)
 guidata(hObject, handles);
 
 %% Update display
-if isfield(handles,'current_detection_file') && any(contains(fname, handles.current_detection_file))
-    loadcalls_Callback(hObject, eventdata, handles, true)
+if isfield(handles,'current_detection_file') && any(ismember(fullfile(fpath, fname), handles.current_detection_file))
+    loadcalls_Callback(hObject, eventdata, handles, 'filename', handles.current_detection_file, 'checkForChanges', false)
 end