What do you mean by "the display says"?
Networks only output in specific resolution. I haven't checked in a long time, but I recall that Fox used to only output their broadcasts in 720p compared to ABC/NBC/CBS which would output in 1080i. Something about the amount of sports Fox broadcasts, in particular NASCAR, where lower resolution progressive is better than higher resolution interlacing. ...or something.
So, if "the display" that you are talking about is the information panel from your cable box or antenna menu as you change channels, then it might just be the resolution from that specific network. If you are talking about menu settings from the TV specifically, then that's another issue.