because the treble clef only goes down so low, if you go into the bass range with whatever you are doing that is midi related, it will go into the bass clef. I'm pretty sure there's no way to change this. try playing your parts up higher for the sake of scoring. it is a general musical issue: if you were to show all notes in the treble clef, you'd have so many ledger lines under the treble staff that it would become insanely difficult to read the music. that is why the grand staff comes into play when scoring parts.