How to switch the transmitter on an rc helicopter?

my helicopter is kick *** its a tandem 3ch military thingy im too lazy to type the rest anyway the trim is messed up cuz whenever i take off the stupid thing goes c razy and spins out of control. Soooooo i wanted to switched to a better transmitter thth i already have tht has an actual nob for a trim thingy ... so if anyone knows to to switch the transmitter on an rc helicopter plz help