open up the gripframe and press the red setup button. scroll down until you see max ROF. press the select button then use the raise and lower buttons to set the ROF then press select to save it.
dwell, debounce etc should be set at the factory settings. if you're gun fires when you slap the back of the tank (with the gun aired, turned on, and eyes off) then raise the debounce until this doesn't happen.