Last week I tried to change a reservation I have and even when AA is known to be airline that overbooks the most they told me that I would have to end up paying $150 dlls. for the change plus the difference if any on my new date. Huge difference when I changed the date for a flight with southwest, I didn't have to pay anything.
Now, I'm thinking in just not using my flight that I couldn't change and just buy another ticket from southwest, it's actually cheaper.
So next time that you're flying keep that in mind and avoid American Airlines