I think we have pretty consistently used “Back” for exiting menus. Exit is so far only used to exit the program. But anyway as I said if we get that confirmation dialog working it won’t be a problem, at most people will accidentally click it once and then learn that “Exit” in thrive menu means exit the program.
I’m not sure who selected the original text. But I would have avoided using Quit at the time, because many games annoyingly make “Quit” mean not quitting the program but just going back to the main menu, which we have a separate button for.