fail safe

I bought this (https://hobbyking.com/en_us/turnigy-9x-9ch-transmitter-w-module-ia8-receiver-mode-2-afdhs-2a-system.html) turnigy 9x and IA8 receiver combo from hobbyking and I can't find a way how to set up failsafe and youtube/google isn't helping either.

Hi, System: Flame wheel F550 Naza-M v2 Naza GPS Spektrum AR 8000 receiver Spektrum DX7i transmitter. The system worked well on my first flight test with one exception. When the transmitter is switched off to simulate loss of signal the F550 does not execute a RTH, but rather goes to F/S...