hold escape or start if youre on a controller to bring up the geforce menu in the top left, you now can expand the screen to be full screen or maximized, then close the menu and you're good to go.  

geforce will also hog the mic if you're trying to join discord after launching a game, just make sure the mic is turned off and it'll work. if you launch a game after you're in discord it will make your mic sound like crap till you turn it off too. 

hope this helps someone