Answer : The answer to this question varies depending on the situation.
1) If you have an HDMI TV you are using as a monitor and have the remote then try this : http://archive.vn/KFCaj
( I did check my TV's settings after I found the remote and under Picture there was an Advanced Settings section where I could turn off Overscan and then the size of my desktop display area within Windows shrinks slightly. )
If that doesn’t work, then what to depends on whether you have an AMD or nVidia graphics card.
( Between them they have virtually 100 % of the video card market, so you almost certainly have one or the other in your PC. )
2) A) AMD Solution : http://archive.vn/Oxw8J
2) B) nVidia Solution : http://archive.vn/CsNSo