You have a signal level issue, probably outside lines/ splitters or storm/ rodent damage.
Verify all connections are tight, Call TTWC and get a tech out... This cannot be fixed over the phone, it's a physical problem.
Remember, pixelation is essentially "errored seconds", when the signal is too weak or corrupted with noise to be understood clearly by the cable box, which means it's an inside and/or outside cable wiring issue. Always good to check behind any wallplate outlets as well for bad fittings, especially if it's just some TVs pixelating in the home and not others.