Throttle FailSafe doesn't work

Transmitter ON and throttle full down, ch3 value is 1965, transmitter off is 1962

The range is too small to set FailSafe correctly (I have tried 1964 doesn’t work)

Could you help me please ?

Radio receiver PPM Radiolink R12DSM

I think that problem soleved by decreasing throotle fail safe in RC settings

No. The problem would be solved by calibrating the sticks to the radio and then setting the proper endpoint values. Ideally you want 1000 at full deflection one way, 1500 centered, and 2000 at full deflection the other way.