Thumb throttle speed on Bafang mid drive motor M500

Hi,
I am looking for help on a Jorvik Mid Drive Electric Mountain Trike JMT7.
It has a mid drive M500 Bafang motor.
The throttle speed is restricted to 4 MPH and I would like to increase the setting to even 10 MPH.
I have looked at the Badass box but it doesn't state if can can increase the thumb throttle speed.
Any help would be appreciated.
Regards, Dave Morton