Saving the files
To save files, you can press Cmd+S keyboard shortcut, or go
to menu File -> Save.
All changed files are saved at once, including files that are not currently selected. Files without changes and read-only files are not saved.
Saving can also change the file creation and modification dates shown in Finder. See File dates vs. Exif dates.
Saving on quitting the app
When you are quitting the application, you will be prompted to save unsaved files. If you decide to do so, Exif Editor waits until the operation is finished before it really quits. If some file cannot be saved, the application does not quit, so you do not lose your changes.