I always watch the same channel every night with sleep timer. For the past 3 nights when I turn it on in the evening it is on a different channel. The same different channel every night. When I woke up this morning I turned it on and it was on the same channel I fell asleep with. I rarely watch this tv during the day and it is not connected to DVR.
It might be from when they refresh the signals overnight depending on when you
fall asleep and the refresh they send out. You can check in your settings. Using your
remote, go to the gear, then Preferences, then General, then scroll down to Daily Update Time and either keep as is or change it. Good luck!