as i know the Proof of stake is about staking an amount of specific coin in the network so it can make decisions what's gonna be in the next block
Not exactly.
You do not take decisions about the next block.
You say that those transaction you put inside that block are valid and you put you coins at stake. Like a bet. If there are invalid transaction there, you lose those coins. This is why it is called proof of stake.
You cannot make decisions like you suggested. You are staking, not deciding anything. You can decide what tx goes inside your block and which doesnt, but your "decision" power dies there.
YOu can read more here:
https://eth.wiki/en/concepts/proof-of-stake-faqs
