Hello Rob,

If you are referring to importing a multi-channel MIDI file, look at the Sequencer window (green SEQ button in bottom toolbar) to see which channel the bass part is on. There is a [...] button under the edit column that allows you to change the note velocities on that channel. However it is probably better to use controllers to accomplish this - either controller 7 (volume) or controller 11 (expression). To do this, open the notation window and click the # button to open the event list editor. You can use the Filter button to only show the bass channel. Then, at the top of the list, either Insert or Edit controller 7/11 to increase the volume of that channel. If it's already at 127 (max) then you would need to reduce the volumes of all the other channels.

Andrew
PG Music Inc.