Both edges of the screen (left and right) are cut off on most channels

I have an HD TV and XR2 remote with non-X1 Xfinity cable box.

I set the aspect ratio on both the TV and the cable box to 16:9 aspect ratio and the edges of the picture are cut off.  I thumbed through the various aspect ratios, but even when the picture is letter boxed or postage stamped the edges are not visible.  It's so annoying that I can't see the score on the baseball game.