Solution . Leave it on lower settings, lol.

Now seriously, I suppose you have both devices connected via HDMI and more likely during "handshaking" everytime you power on them, the TV forces the box to select the lower settings. I am also assuming the TV native resolution is 720p and among other things hence this behavior. Check all settings in the menu for both devices just in case.

Several issues have been reported regarding HDMI and this Cox/STB but could not find an specific explanation on the net.