Hi, Manfred:

Midi Channel 10 is the General Midi standard for drum tracks. Depending on what sound source you have, it may be possible to use a different channel, but you would have to be able to assign the drum sounds to that channel on your sound source. For instance, on my Casio CTK 651, the drum kits are Program numbers 160-167, or Bank 3, Programs 1-8. These can be selected in Composer.

As simpler way to make the B natural bass drum quieter than the rest, is to use Shift-V to show the velocity values for each note, select the B-naturals in your track and use L-down arrow to lower the velocities of the B-naturals. That should do the trick.

Good Luck

David