How to change aspect ratio on Panasonic th-50px80u TV

[Markdk7]

The aspect ratio on my tv is messed up (the picture is too big for the screen). Any idea how to fix the aspect ratio? Maybe by factory resetting? I know there's a "zoom adjust" option in picture settings, but it's grayed out, despite being for an HDMI input with a 1080p signal (a Roku). I don't have the remote, but will buy one if absolutely need be. Some picture for reference.

 

[rgd1101]

do you mean resolution? the tv is only 720p