Hello Peter,
QMidi exports AAC with a fixed bitrate of 128 kbps. If you need more control other target audio settings, you can simply use another tool, like iTunes, QuickTime, ecc, to convert your wav file.
See also:
http://qmidi-forum.1128731.n5.nabble.com/Movie-export-settings-td510.html
Mixage Software
www.mixagesoftware.com
support@mixagesoftware.com