Hi there,
May I ask what the model number of the TV is?
For using a TV as a monitor you want to have a hunt through the menu for a "PC mode" or an option to rename one of the HDMI inputs to be "PC" as this will make the image look nicer.
You will also want to enable 1:1 pixel mapping, which will be called something like "screen fit" or "just scan" - as this removes any over/underscan on the TV's side.
For the settings I would have a look around for some recommended settings that people have posted up, but generally I would say look for options like "edge enhancer" or "noise reduction" and turn them off. These features are good for applying to SD video - but for a full-resolution PC image they just make things look worse.