I want to disable the preference "Copy files to iTunes Media folder when adding to library" in iTunes Preferences > Advanced.
However, every time I uncheck the box and click OK, it seems to refuse to disable this feature. The box is checked again if I immediately go back to the screen.
Is there some way to disable this via a plist file? Or should I reinstall iTunes somehow?
FYI: I am running iTunes Version 126.96.36.199 on MacOS Mojave 10.14.4, on a 2018 Mac Mini restored from a 2011 iMac that ran High Sierra before it died. As I've had my iTunes library running over several years, I'm guessing that there may be some configuration bug somewhere.