I set a password for root to allow me to change the login name pi. When I login as root, the menu bar flashes several times and then disappears. I have tried several key combinations to bring the menu bar back, to no avail. The only response I can get is the new file, new menu, etc. window by right clicking on the desktop. Logging in to pi still works as it should. It is probably something simple, but since I am new to the pi, I do not know all the tricks yet. Any help would be appreciated.
Debian does NOT have a root login (for good reasons) but there should be no need to ever login as root.
No distribution allows root to use a GUI. It may be possible, but you will not find "something simple".
Incidentally 'chang(ing) the login name pi" is not simple, nor is it recommended.
If you want another user create one, and leave
Edit: ALWAYS change the default password for 'pi' even if you never plan to use it on-going. It's a well known password and standard hack vector now.