Can local properties change themselves?

I very much suspect the answer is ‘no’. However, on a few occasions I have casually checked that my full score settings for local properties are still set to ‘Globally’ and noticed that they now showed ‘Locally’. It is a setting I don’t use for full scores, and I never have any recollection of changing to it. I can’t find any mention of a keyboard shortcut to toggle between the two scopes, but is there a setting somewhere that defaults the setting to local under certain circumstances?

The state of Set local properties is saved in the project and so your existing setting is restored when you reopen the project. There’s no default key command to change the value, though if I remember correctly it is possible to define a key command to toggle between them.