Currently on 8.0, you can't connect the Roku to a different TV, set the Display mode to 720P, and then expect the setting to stay at 720P if you move the Roku back to the original TV. If you are not seeing an image when connected to the TV, try the remote button presses already mentioned. To see what those button presses do. Hook the Roku up to a 1080p capable TV and then watch the TV while pressing the buttons. You will see it is navigating you through the settings menus and attempting to select 720P.