Cetus X not flying correctly

[Coolhand20]

I just bought a Cetus X. When I arm it, it of course spins slow. As I inch the throttle up and I mean in micro movements it starts to speed up and then all of a sudden. Full power and up to the heavens. I have made sure they are on the same firmware. I played with the mid and expo I believe it is called. I tried many variations of settings and nothing worked. Any ideas?