Hi Bieomax, unfortunately that is the epa for the steering servo, not the throttle. There isn't a user settable throttle adjustment but interesting to see from your photo a couple of potentiometers on the transmitter PCB.
Time to dismantle mine I think and have a tinker - if one is for a throttle epa then perhaps a strategically drilled hole in the case and a small screwdriver in my pocket may give me the field adjustment I'm hoping for.
Currently I've got half an eraser on an elastic band under the throttle switch which'll beg the question from my son 'what's that for?''!