I can access mine by using a Q.Menu button..
I then have a resolution option , I go to "select by channel" which also has all possible inputs ( AV 1,2 ,RGB 1,2 HDMI 1,2,3 etc)
and then choose HDMI 1.. and I make sure that it's on 1080P
I make sure that it's the same in every MODE (game, flat ,cinema..)