Locate the shortcut to HLA Fusion 4.2 on your desktop, then right-click on it and select Properties.
Go into the Compatibility tab...
Then toward the bottom of the window, click Change high DPI settings:
You'll want to tick the box for, "Override high DPI scaling behavior. Scaling performed by: Application" (Circled in green near the bottom of the window)
Click OK, then click OK again, and re-launch HLA Fusion.