You really can't 'select' alternate voicings. You can sort of fool the machine by using a substitute chord and then adding your root bass note, say you don't like the way D sounds so you might sub it out for a Bm7 with a D bass.Sometimes that works. The program will change chord voicings on it's own for the screwest reasons. If you add a special bass line or even a note in one part of the song, that will sometimes change chord voicings in another part of the song. Making the chord play twice (or more) will also sometimes change the chord sound, too. Even a change in beat also changes the voicing as well as bass line. It's the way it is.