the airport customization .INI files are read from BOTH folders, using this order of priority:
- First in the local \scenery folder, together with the scenery .BGL files
- Then, if an .INI file for the same ICAO+AFCAD combination is found in the %APPDATA%\Virtuali\GSX folder, this one will take precedence over the one in the scenery folder
The reason for this priority system, is twofolds:
1) If your scenery is installed under the main sim folder, which is installed in the default location under C:\Program Files, there will be permission issues if we tried to store an .INI file there. And it would be against UAC rules that no application should try to write into its own folder, but use the %APPDATA% folder instead.
AND
2) Scenery developers might want to include a GSX .INI file together with their scenery, and the \scenery folder is the most logical option. This file should be considered to be "read-only" but, this doesn't mean you cannot further customize it. In fact, you can and, as soon as you start customizing an airport which was provided with a GSX .INI file in the \scenery folder, a NEW .INI file BASED on it will be created under the %APPDATA%\Virtuali\GSX folder, so GSX will start reading from that file from now on.
This means, if you choose to Undo all your changes, the original .INI file in the \scenery folder will still be there, so you will not start from scratch, but from at least a good base made by the original scenery developer.
This way, we can respect all Microsoft recommendations about UAC, allow 3rd party developers to customize their scenery for GSX, and allow users to further customize it, but keeping a "backup" they can go back to, in case something goes wrong.