The problem is your registry. By default, the registry key for the sim has a trailing backslash, like this:
C:\Prepar3D v4\
But yours, maybe because it was altered by some utility or by hand, is missing it, so the Control Panel is confused. We'll fix it to defend against this, but you can probably fix it yourself by adding the missing trailing backslash in the two P3D4 registry keys, here:
HKEY_CURRENT_USER\Software\Lockheed Martin\Prepar3D v4\AppPath
HKEY_LOCAL_MACHINE\SOFTWARE\Lockheed Martin\Prepar3D v4\SetupPath