You can adjust KDW or NN. Here is what the manual says:

KDW (Throttle Pull Rate) – KDW can be changed using up or down keys. The higher the value, the more aggressive the control. Heavy boats may need higher values. Factory setting is about 80. Normal range is 80 – 200.

NN (Paddle wheel Filter Factor) – NN is set at about 120. The higher the value the more filtering is done. If you feel you boat is surging a little too much, raise value by 20 or 30. If you feel the speed is slowly drifting around too much, try a lower value to tighten control.
Also talk to the guys at Perfect Pass, they have excellent customer service.