You have to use the Seq Button (Sequencer) in Biab if you want to change midi data/channels etc.

When you select a style to play with the midi, Biab will ask if you want to use Biab to play along with the midi or not.

If the original midi file has the same channels as Biab uses, there is a chance that it was made with Biab to begin with. Do a song search for it with Biab format .mgu and you will probably find the original Biab file.

Trax