I’ve never had RM8 so cannot run a comparison, but with other (usually older) applications the following has worked. For RM9 do the following.
Navigate to C:\program files (x86)\RootsMagic 9
Right click ‘RootsMagic.exe’
select ‘Properties’
Select ‘Compatibility’
Click ‘Change high DPI settings’
In the ‘High DPI scaling override’ section enable the ‘Override high DPI scaling behaviour’
click OK
click OK
If it doesn’t make any difference then restore that to how it was and hope that someone else has a better idea!
Rob