This sounds like the parameter config file is corrupted.  This is stored in two places.  Lets try the easy fix first.   With PC Link closed, Type this into the windows search bar and hit enter: %AppData%  That should take you to the roaming folder.  Find the PCLink folder in there and delete the two files that are in there - should be "DefaultParameterConfig & Options2".   Open PC Link again and these files will be recreated.  See if that solves your scaling/colour problem.  If not