It sounds from your OP that you may have a mode 1 transmitter. Easy way to tell is to see whether the left or right stick does not centre itself when you push it up or down and release. The one that does not self centre is the throttle

On a mode 1 transmitter the throttle is on the right hand stick, so this one will stay put when deflected up or down. The opposite is the case for mode 2, the non centreing stick is on the left (with the Tx facing you).

You don't say if this is a new radio or not. If new and you have got the wrong mode take it back and ask the dealer to exchange it. Because of the non self centring of the throttle stick you cannot just change some settings to change modes.

Good luck

Terry