AI-generated summary
To summarize, you cannot change your username when logging in with an email, but you can after upgrading to a wallet. Once upgraded to a wallet, you cannot log in with the original email. Use MetaMask for wallet login, backup private key and seed phrase, use an out-of-region Apple ID for MetaMask on iOS, manually add $CSB to MetaMask on other devices, use a proxy for xLog App wallet connection on mobile, bind to root domain, use Markdown syntax, and refill CSB balance at https://faucet.crossbell.io when low.