Which version of MuseScore, what OS?
What steps are you trying and in which way do they fail?
Educated guess:
Are you by chance using an AppImage in Linux and changes to shorcuts are noch saved, so not available in the next session?
If so, we most probably are looking at a permissions/ownership issue, the (path to the) shortcuts.xml not being writable to you as a consequence.
Comments
Which version of MuseScore, what OS?
What steps are you trying and in which way do they fail?
Educated guess:
Are you by chance using an AppImage in Linux and changes to shorcuts are noch saved, so not available in the next session?
If so, we most probably are looking at a permissions/ownership issue, the (path to the) shortcuts.xml not being writable to you as a consequence.