If you adjust the GSX.CFG file in the airplane folder, but you also have a GSX.CFG file in the %APPDATA%\Virtuali\Airplanes folder (which you should have, if you edited the file using the GSX airplane configuration editor), the changes won't be seen, because the file in the %APPDATA%\Virtuali\Airplanes folder will always take precedence over the one in the Airplane folder.
However, there's no need to edit the GSX.CFG file directly, because the GSX airplane configuration editor will surely save the settings correctly, assuming you pressed the Save button, of course.