You need to go and turn OFF all the arranger parts other than Drums and A. Bass....

Your manual will tell you how to do this....

Alternatively, if your left hand (or right!) is up for it, why not just use the Drum parts, and PLAY a nice bass line? Trust me, it will be far more realistic that the arranger's bass line if your chops can cut it, because you can now lead with the bass voice, rather than it always follow your changes.

In other words, YOU know in advance where the changes are going, so the bass line can walk to it, or point towards it, whereas arranger basslines only know the chord you are playing NOW, not where they are supposed to go. For me, it's the biggest difference between a live band and an arranger, and the reason I play a LOT of LH bass.....