I'm not sure about changing the chords entirely but on the song page if you click the chord diagram of the chord you wish to alter it will give you a choice of alternate fingerings for that chord. Click on the variation you would like to use and it will substitute it for you. Hope it helps! Peace!
[b][color=#FF0000]If your brain is part of the process, you're missing it. You should play like a drowning man, struggling to reach shore. If you can trap that feeling, then you have something.
[/color][/b] [b]Peace of mind. That's my piece of mind...[/b]