how can I properly format my TV?

I have a 55" HD Panasonic Flat Screen and I can't seem to format the picture correctly. The format button on the remote gives me 4 choices, FULL being the only one that gives me close to a full screen. What am I missing here? If there are words on my screen, or even credits, I can't even make them out because only 3/4 of the sentences appear on screen. The channel icons are mostly obscured, It's like watching a show with 30% of what you were intended to see blocked out on each side of the screen. Help!!