If you have an NVIDIA GPU (Graphics card) do this:
- Right click your desktop
Click NVIDIA Control Panel
Go to 'Adjust desktop size and position'
Select the display you want to change
On the 'Scaling' tab, choose Aspect Ratio
In the 'Perform scaling on' drop down, choose GPU
Check 'Override the scaling mode set by games and programs'
If you find other solutions, post them here.