FeRo, not sure if this can help. I recently reinstalled my P3D completely and had the same problem.
Couldn't set anything, couldn't get the edit function to work.
Make sure that your P3D.exe file runs 100% as administrator (I set every user to full permissions [incl special permissions]).
I did the same with the Ezdok configuration tool and the EZCA.exe file.
Once this was done and a reboot performed all functions are back
cheers
Peter