If the alt-coin is based on Bitcoin then it will follow Bitcoin's data structures. In bitcoin, the only thing to "control" is a user's address and wallet using your private keys to sign transactions. Transactions only transfer UTXOs and don't change anything in a historic block. Protocol changes ("control that chain") means changes to the consensus rules. Those generally require an upgrade of the client you are running as well as what the majority is running.
I think you are talking about Ethereum based coins. There you have the concept of contracts that can be over-written by the developer that deploys them to change to whatever they want.
Not not tokens. Coins based on bitcoin
I don't know if i should take you seriously but now that you claim to have used them yourself, care to explain how exactly does that function when the "genesis block" or any "block" for that matter is essentially supposed to be immutable.
Your private key only controls a set of UTXOs that you generate from the wallet. Theoretically, maybe you could have set of consensus rules be governed by a pointer and updating it can change the consensus rule. But then, that is not Bitcoin OR a Bitcoin fork. That'll just be something else with code copied from Bitcoin.
Also, looking at your post history, it feels like you are just randomly asking "technical questions" to either fish for merit or you mistakenly believe that you could "reverse engineer" a public key to a private key; only if you knew some deep secret lurking in the Technical discussions section.
