First, your tool is great !!! (But a little constructive criticism doesn't hurt, does it

The subject says it all ...
I tried to use XnView with Windows XP (Installed as Administrator - used by all users). I quickly found that only administrators can save options.
This is not surprising, since the options are stored in an .ini-file in the program directory (where only administrators have write access).
Please consider to either use user based ini-files (stored in the users' profiles directory) or saving options into the HCU branch of the registry.