Which Pix Shape?

I own a model 50842 and am having a problem finding the correct aspect ratio to use. I currently only watch dvds on this television and with the exception of a few of my daughters I only watch dvds in widescreen format. It seems like I'm constantly having to use the pix shape button on the remote. I dont mind the black bars on the top and bottom of the screen but when they are huge I do mind. The giant black bars typically are on the new releases as my collection of widescreen dvds have the bars too but are a lot smaller. I dont even know.which of the 7 pix shapes is intended for watching dvds. What I do know is that to see a film as it was intented requires me to.have much of the screen lost to the giant bars defeating the purpose of buying a large television. Is there a solution? Are there pix shapes.specific.to.a particular input?