I'm sorry for the inconvenience, yaminoyugi! It sounds like it's just a Picture size issue There's an option within the picture menu for Picture size you're going to want to make sure that's set to 16X9. If it is set that way and you're still receiving the same issue you would need to contact you cable service provider to walk you through changing the output resolution of the cable box.
Hope this helps!
I recently bought a Samsung Smart tv. The past week we had issues with the broadband so we had a tech come out yesterday and switch the DVR boxes. She switched the main DVR so it is next to the modem, and now our t.v. had to reset. The picture is too large for the set. The top and bottom are cut off and we don't know how to set the resolution back to 1080p. Is this because of her new equipment attached to the new t.v. that we can't do it again? Or am I looking in the wrong area for 1080p?