1) From the graphics drop down select Desktops & Display. 2) At the bottom where you see a small monitor icon, click the little triangle at the top right corner. Click on configure in this menu. 3) You should now be at an Attributes menu, at the top, click Scaling options. You should now see scaling options. 4) Click the scroll bar and try dragging it around to scale your screen.
It may be your HDMI monitor or TV is set to enforce 16:9 ratio
1. Make sure your resolution is 1920x1080 2. Go into your TV/monitor and change from 16:9 to allow it to scan the input. (On my LG TV it is called "Just Scan"