Glad you and your lad are having fun! Just had a browse of the manual and this might be useful , also check the epa is set at 100% for throttle reverse and steering in both directions.
Settings are changed by means of the “SEL”, “CH”, “+” and “-“ buttons.
1. Press +/- to select the desired model. You have the choice of 15 memory spaces. The model number and model name are indicated on the LCD display.
2. Press “SEL” to take you to the desired setting. The following functions are available for selection:
a) “REV” setting (reverse direction of servo rotation)
Press the “CH” button and choose between ST, TH or 3C and
4C. Press +/- for normal or reverse. 4.
b) “EPA” setting (servo travel limiter)
Press the “CH” button and choose between TH or ST. To select the direction of rotation, the throttle must be to the front or back with TH, and the steering wheel must be moved left or right with ST. The display shows LFU for left and forwards and RBU for right and brake. The desired value can be set between 0 and 120% by means of +/-.