To update the email address on your TurboTax account, you will need to find the Intuit Account option from the left-side menu.
If you have just logged into turbotax.com, click on Intuit Account in the lower left corner. This will open Account Settings. Click on the Edit button to the right of your email address.
Or, if you are already viewing your return, click on Tax Home in the upper right corner. Then click on Intuit Account in the lower left. This will open Account Settings. Click on the Edit button to the right of your email address.