You try to edit the Mate menu but nothing happens, trying both from the control center and with right click on the menu button.
The problem lies in the ~/.config/menu that for some reasons change ownership to root. You only have to reverse the permission to the normal user
sudo chown ~/.config/menu `whoami`:`whoami`
Shouldn't work, retry with
sudo chown -R ~/.config/menu `whoami`:`whoami`
For non-experts: `whoami` is written between backticks: don't use apostrophe for that! On the US and UK Keyboards is on the left of the 1 key.
For italian users: su tastiera italiana si fa con ALTGR + ' (that's why I changed nation! )