Allow/clarify adoption of existing settings folder in paths

[atomicthumbs]

I use a Mac. I have some portable installations of XnViewMP on external drives to allow portability between computers, with the settings and database stored on the drive. When upgrading, since I have to replace the app in-place, I have trouble determining whether the portable installation will start using my ~/.config settings folder or the portable settings folder. When I switch the setting from "current user" to "portable" or "custom" and select a folder with XnViewMP's files already in it, it's unclear whether it will adopt that folder's settings and database, or overwrite them with the ones from my user folder.

Some clarification on this would make this situation easier.

[user0]

app checks folders in order and loads settings file wherever it is found first
eg in windows:
1. application folder
2. local machine folder
3. current user folder (registry)