Cannot change window manager

[danielsender]

I just installed 18.04 on a Lenovo laptop. I need to become more familiar so I can issue an opinion about it. So far I encountered a problem that I don't know how to solve. For userA, I cannot change the window manager, if I click on Gnome Classic I still get the Ubuntu option. On the other hand, for userB I can switch from one manager to the other without problems. What should i do for userA in order to fix that?

Thanks in advance

[danielsender]

I found https://www.ostechnix.com/reset-linux-desktop-default-settings-single-command/ that made the trick.