Speed controls
some esc's, particularly the cheap end ones (unfortunately those blue case ones have a rep to emit the black magic smoke) have a reduced reverse, to protect the model in the event of knocking the stick etc, so you don't get full tilt into the wall or bank😱
If you have the max speed in reverse, then you need to swop any two wires if its a brushless motor, and then reverse the channel on the transmitter, max speed is always forward, so its a fundamental set up issue here. You also need to ensure the stall or max amp draw is within the tolerances of the esc stated amperage, and be mindful that Chinese esc's generally have a very over exaggerated stated specification. in the set up programme of the esc, you can usually change the direction here, its going to take a bit of fiddling, but its achievable