Your first statement is confusing. Why do you say your digital cable is 720p only? You should have 3 output options to select if you want HD: 720p, 1080i, or native. I have my sat box on native, but there is a slight delay when changing channels. If that bothers you, set your output to either of the other two. Most programming is probably in 1080i, but you almost certainly would not see any difference between outputting 1080i or 720p. 😉
I agree w/ Dave3putt .... it may be that you've "selected" the Quick Setup ..OR.. that set top box had "defaulted?"
On my two new Cisco Explorer 8642 HDC hard drives {or, the previous, older Scientific Atlanta 8300HD's} - - - there exists an "Advanced" mode selection wherein YOU go through a much more detailed one, deciding "accept" or "decline" for those signal inputs as David explained as well as all-of-the different display sizing criteria?
Consider asking for "tech Help" @ Your T.W./ Roadrunner Service there in Hawaii?
