Why are my HD channels not fitting my HDTV screen?

Question

its a 46" LG HDTV.

Answer 1

Oversized?

Check one of two places...Your TV remote should have a button labled aspect or size...press it again and again and it will CYCLE thru several picture sizes.....

Then there's the Cable Box / Satellite box....

That's a real pain to describe how to get to the Video Settings and select Aspect and set it to 16:9

On mine, it's easy because I have done it several times.....

For you, a phone call to your service provide is the best way to get it done.