Audio snap bpm vocal clip

[Marcvs]

Hi, 

despite I've watched a couple of video tutorials about audio snap, I still keep experimenting that the vocal clip sometimes doesn't "respect" the bpm and goes faster and does not follow the rest of the midi tracks or (this is more curious) I even hear my same voice faster and duplicated 2

I'm a rookie as you can see ?

Thanks in advance if you want to give me some advice.

Mark