Hello, thanks for the screenshots - I can see exactly what is happening here. It isn't your text being ignored; two things are interacting:
On macOS, any menu item whose Role is Quit is automatically moved out of the File menu and into the application menu (the one named after your app, beside the Apple menu), following standard macOS conventions. So a Quit-role item will never appear inside the File menu at run time.
Your project already contains a Quit item. The File menu created by the New Project template ends with one, and on your machine its text is "Exit". When more than one item has Role = Quit, only the first of them is moved into the application menu and in the version you're using the extra one is not shown. So the "Exit" you keep seeing at run time is that original item, not the one you are editing - that's why the caption never changes no matter what you type.
To get your own caption right now, open the Menu Bar editor, select the original item at the bottom of the File menu (the one currently reading "Exit"), and change its Text there. Keep exactly one item with Role = Quit and the application menu will show your text.
If you'd rather have the command stay inside the File menu with your own caption on every platform, set the item's Role to None and put System.Quit() in its Pressed event handler instead.
I've also fixed the underlying surprise for the next release: an extra Quit item now stays in the menu where you added it and keeps working, instead of being hidden.
https://feedback.objo.dev/bug/1574
