Suggestion: Do not ask to save changes when closing a blank score
When you first open MuseScore 3, it automatically creates a blank score. Most of the time, I find myself wanting to open an existing score. Once I do this, I then want to close the default blank score that opens automatically, and every time I do this, MuseScore 3 always asks if I want to save the changes made to "Untitled" before closing it, even though I made no changes to it.
I would recommend either not opening a blank default score unless you specifically choose that option in the startup menu, or not asking the user to save changes to it if they haven't actually made changes to it.