I'm using my linux only managed by root user (I know is not the best practice).
The first point is, since beginning, my gdm is not showing root user on the initial list, so there is not available users on initial list. How can I set root to appear on the list or selected by default?
Here is a screenshot of what I'm talking about. It only shows "Is not on the list?" (sorry, screenshots are in spanish), so I must click there to type root.

The second point is, I want to use gnome-classic by default but now I must select it always and it is not remembering last login. I read it should remember... is because is root user? How can I put gnome-classic as default environment?

I tried so many things... editing /var/lib/AccountsService/users/root and putting XSession=gnome-classic
This is the content of my /usr/share/xsessions dir:
gnome-classic.desktop icewm-session.desktop sle-classic.desktop
gnome.desktop icewm.desktop xsession.desktop
So the gnome-classic is there... I don't know how to make it work as default.
Thank you.