Well the easiest fix is to not use HDMI. I have no idea why people insist on doing this for monitors its crazy. But if you insist. From AMDs forums.
https://community.amd.com/thread/198719
Since Radeon Software Crimson Edition 16.5.1, the HDMI Scaling slider has been moved to Radeon Settings under the Display tab.
If you do not have the HDMI Scaling Slider, it could be due to the following:
You are currently running at a 4K resolution. HDMI Scaling is not supported at this resolution.
You are currently running in an Interlaced display mode (eg. 1080i). HDMI Scaling only supports Progressive display modes (eg. 1080p).
NOTE: If you need to run your display in Interlaced mode, we suggest reverting to Radeon Software Crimson Edition 16.3.2.
You are currently using the Windows 10 scaling feature. This feature is enabled by default in Windows 10 which allows the OS to handle display scaling.
If you would like to control scaling using Radeon Settings, please do the following:
Right click on a blank area of your desktop and select "Display Properties"
Select "Advanced Display Settings"
Select "Display Adapter Properties"
Click on "List all Modes"
Select the preferred display mode. (If it is already set to your preferred display mode, simply select a different mode and click OK. Then reselect your preferred mode. NOTE: 4K resolutions are not supported)
When you do this, the Operating System hands over control of scaling to the graphics driver. In Radeon Settings, the HDMI scaling slider should now be available.