If you're able to log in, you can update your email address in the account settings.
- Log in and in the left menu column scroll down to Intuit Account.
- In the account settings go to left menu column and choose tab Sign In and Security.
- You can update various things there including email address.
- If you change your email address, it may at first say "unverified" beside it. If you click on that word, it will send you a link or code so you can verify the email address. It should give you the instructions.