Did you try the format button on the remote to see if that helps. If it doesn't you may have to change the resolution on the Mac to get the desktop to fit better . Choose the resolution that matches the native resolution of your TV. For example, if you have a 1080p TV with a 16:9 aspect ratio (which you do) choose a 1920x1080 resolution. Connect the computer to the display then go to displays in system preferences and there should be a group of resolution settings that you can change to get your computer to fit better, though keep in mind it won't be perfect since most computers won't match the 1920x1080 of 1080p displays.