Probably I did it the most fuzzy way… I saved my SD-Card (or at least the Songs getting edited) as backup on harddisk. Then I used the BeatBuddyManager to adjust the parts. It wasn‘t hardly worth the time and the trouble at home… I would recommend editing on a DAW and re-import it to BB, but as I‘m not very common with software and the whole IT-stuff I did it that clumpsy way.
BTW there was a download-link anywhere in the Forum where you can get a improved MIDI-Editor for the BB. It allowed me to adjust the volume of the instruments in general (instead every single note with the BBManager).