There are two ways to adjust the picture.

One is with the television - which it sounds as if you have tried with little success.

The other is the source - the unit providing the picture, and how THAT sends the signal. Many cable boxes, DVD players, Blu-Ray players and other peripherals ALSO have a menu where you can adjust the aspect ratio. If you're looking for a widescreen picture as the final result, set the TV on 16x9, and then adjust the menu settings of the other unit.

Does that help?