When you log in, choose "Intuit Account" in the left column. Then choose "Sign In and Security." On the screen called Sign In Info, on the line that displays your email address, click on your email address. Do you get a popup? If nothing happens, is there an arrow on the right side of the email address? If so, click that little arrow.. A popup should appear to enter and confirm an email address and then SAVE. It will also ask for your password for security.
