This is how you set up your receiver to APM and APM to servos using (Spectrum Receivers)

Receiver out to APM2:

Aileron -> APM Ch.1

Elevator -> APM Ch.2

AUX1 (Pitch) -> APM Ch.3

Rudder -> APM Ch.4

Gear (Gyro) -> APM Ch.5 for flight mode switching.

Throttle -> Directly connect to the ESC

APM2 to Servos

Ch1 -> Front Left Servo

Ch2 -> Front Right Servo

Ch3 -> Rear Servo

Ch4 -> Rudder

DX8 Settings.  Just the default will do, which has the "Normal" for swashplate setting