Write down the new public address and backup seed phrase (BIP39 mnemonic) on paper or metal.
Send all funds from old to new. Pay appropriate network fees. 16jy7qljnxb7chzyqbp8qca9d51gajyxqn private key upd
If you have a valid private key (real one) that needs updating, follow this process: Write down the new public address and backup
Send a tiny transaction from old address to new address. Wait for confirmation. 16jy7qljnxb7chzyqbp8qca9d51gajyxqn private key upd