.air file troubles with fs design studio and aam.

I'm sorry if this is the wrong place to post this, I have been having troubles with making an aircraft for fs2004 useing fsds flight sim design studio and aircraft airfile manager. I got the dummy plane made and gave it the adaptions of an extra300 and all works fine until I try and change or modify the .air file in the dummy aircraft folder, I can't seam to change it or modify it, I will make changes but none of the changes I make will work and if I delete the file the plane doesn't show up and if I replace it with another aircraft .air file and rename it still no changes. Can someone please help me? ❓ 😕