If you change some settings, save them, and go back to restore them to their initial values (as far as I can tell, that doesn't necessarily mean the default settings but probably the ones you started the game session with), the Save button is disabled.
If you change some settings, save them, and go back to restore them to their initial values (as far as I can tell, that doesn't necessarily mean the default settings but probably the ones you started the game session with), the Save button is disabled.