Dual Monitor issue (short cut keys?)

I am running DaVinci Resolve 15.0.1 on Ubuntu 18.04 and have set up dual monitors. However, I just get the one work screen. When I do an 'alt + tab', I can see the second screen, but it only brings the same one when I actually toggle to it. So far, I cannot go into single screen mode because the screen that has those options is on the one I cannot get to. Moreover, I cannot even shut the program down because that is on the other work screen as well. Is there a shortcut key combination to toggle between screens?

Just to clarify, I do have dual monitors functioning, and I did toggle DR to dual screen mode when I first launched it--but it just gives me the one screen. So Resolve will always be Resolve, goodness love 'em, but I still need to get to that other workspace.