What should I do?

I have a three yr old son that is really stubborn. He does s'times 'eat my head'that he never listen to any instructions like when I tell him to to do some thing that is not pleasing or mannerless, he will tell me things like, dont tell that, dont tell me this,he's just big heeded.Pls advise what to do.
The whole saga started when he had to stay with his grandma,so my in laws who are also young are mannerless so I think he picked those habbits from there.He had to stay with her because I was working.
Before he was a good sweet boy

Most 2 1/2 and 3 year olds I've known have gone through this stage. You just have to show them who's boss. I babysat my fiance's goddaughter who is 3. When I would ask her to do something or not do something she would just laugh and say no. SO I'd end up taking away her favorite toy or she wouldn't get cookies that day etc. Then she would straighten up and go 'ok' and do what she was asked.

yeah you got to let that kid know your the boss and make hime do it