WOW! tv+:
Go to the WOW! tv+ settings (by selecting the ‘gear’ icon on the home page), select Device Preferences and then Display Settings. Select the Overscan option and use the ‘X’ and ‘Y’ increase and decrease buttons to adjust the size of your display.
Other Digital Receivers:
Just press the # key on your remote control to switch between wide-screen and regular-screen formats, depending on the aspect ratio (16:9 or 4:3) of the program you are watching.
You can also change your display by pressing Settings to access the Quick Settings menu. Scroll to Picture Size then press the < or > to view the Stretch and Zoom options.