How to fix Unity locked disabled settings?
Solution 1:
It seems that your ~/.config/dconf/user* files are corrupted. Try the following command, it should recreate a new one and allow you to store your settings persistently:
mv ~/.config/dconf/ ~/.config/dconf.bak
Note that you may loose some customization that you may have set on your system as all of them will be reset.
If it does not solve your problem all you have to do is:
mv ~/.config/dconf.bak ~/.config/dconf/