When in Full Screen you can try pressing Shift-Command-M to toggle the hide flag on the "Hide Menu Bar in Full Screen" command as shown in the image below.
The other option is to switch to Single Window view (Control-Command-F or Control-Command-Enter) and then adjust the "Full Screen Minibar" and or the "Hide Menu Bar in Full Screen" View menu commands and then return to Full Screen.
(Click image to enlarge.)
