HD TV letterboxed on SD channels

[jeffbpdguns]

I have 2 Panosonic HD TV's and they have always shown the SD channels full screen, not letter boxed. Now suddenly one of them shows any channel that has an associated HD channel letterboxed but the channels that don't have an HD channel full screen.  All HD channels work fine full screen.  I have tried switching the video controls in the settings screen Video controls from 1080p to 480 and then back to 720 and it works for a day or two and then goes back to letterbox. now no matter what I do any channel that has an associated HD channel is letterbox and it records that way on the DVR, (HD records but uses a ton of space).

Is this something different from FIOS or is it in my box?

[CRobGauth]

What model STB do you have?

[Edg1]

Not sure why it would change but on your remote hit Menu/Settings/Audio and Video/Video Settings/Sd Override/and change to Stretch. This will stretch standard channels to fit the whole screen.