Can't interact with widget/buttons on screen and can't full screen either (help)

Can you show us the Configuration in the Widget Editor?
Specifically, “Visibility”.
There is “Not Hit Test Visible (which is not what you want)” and most likely being used here.
You want it definitely to be “Visible” and there should be nothing but a “non hit test” panel as parent for testing this out.

if anything else is going on here, please provide some screenshots of the settings or setup you made.