peterned100,

If you're using a cable/sat box, often times these settings can be programmed in the box's output menu.

If you're using a straight co-ax, unfortunately it may require a toggle if the broadcaster is sending the signal as a 4:3 or 16x9, and they vary from channel to channel.

There is no option for the individual channel, at least as far as setting an aspect ratio, in the television menu.

--HDTech