The aspect ratio of a high-definition picture displayed on the TV is determined by the signal being received. The TV will automatically adjust the aspect ratio when viewing a high definition broadcast. The aspect ratio can only be changed on the TV if the signal being received is 480p or 480i. Otherwise, it cannot be changed on the TV.
Some TVs have a Zoom or Wide option that will allow you to fill the screen with the image. Refer to the specifications or supplied operations guide for more information. Manuals are posted on your model support page.
NOTE: If using a digital set-top box, the aspect ratio can be changed from within the menu of the set-top box. Consult the instruction manual for the digital set-top box for further information.