You can delete (or at least reduce) the midi volume. Window>Open Event List will show your midi tracks. At the start of each track (111, measure 1, beat 1) you will see midi volume (look down the Length/Info column to find it). I would delete it, but if you want to just change its volume do so under VAL (its value, not ch-channel nor num-number).

You can also reduce the velocity of the midi notes within each track, View>Show Inspector, Region (top left). Velocity is underneath Transpose. Depending on the sample you have mapped this track to, it might change the sound making it more mellow (as if played more softer) and could make it distort less if high velocities were triggering the samples to be played loudly. If you see clipping in the mixer for that track, you can reduce its volume with its slider.

(I have deleted your screenshot as it did not show up to view for some reason)