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I turned on my secondary TV which uses the Cox Contour 2 mini box. I observed that the screen display size was formatted larger than the TV screen itself: parts of the picture was "off the sides" of the TV screen. I chatted with Cox and she set a signal thru which did not change the picture. I was able to resize the picture by changing the video output to 720p from the original 1080p. But, when turning the TV off and then on, it reformatted to 1080p with an indication that the "normal' setting is 1080p and to adjust the video output to the same. Cox rep surmised the problem might be that the mini box is not auto formatting the 1080p to fit my TV's screen size as it did when first installed. Primary TV is set for 1080p and works fine. I do have an appointment with Cox to have a new mini delivered for me to hook up on Monday. Narrows it down to the box?
Use your television remote to adjust the aspect ratio (not the mini-box remote). The setting should be retained when you turn the TV off and back on, so you should only need to adjust it once.
I'm not familiar with the Mini Box or its latest updates. Sometimes when a box gets an update, the video settings default to an odd setting. Your problem reads like Contour had zoomed the video. There should be an option for Zoom in the settings but I thought auto-zoom only applied to channels with SD...4:3 aspect ratios (square)...and not 16:9.
That's not to say you can't zoom an HD video with the remote so perhaps you could have mistakenly pressed the HD Zoom button on the remote. I don't have that option on my current remote...nor do I know if it's on the Mini Box remote...but my previous remote had it.