It all depends on whether the helicopter is a virtual one for FMS or a real R/C one.
If it is virtual:
Select "Controls" on the top FMS toolbar
Select "Analog Control"
Switch the channel numbers around in the bottom four boxes to get the mode you want.
If it is R/C:
Re-program the transmitter for the mode you want
If it is not programmable, switch the servo connectors around on the receiver to get the mode you want.