After I sign in here: https://www.intuit.com/sign-in/I go here: https://accounts.intuit.comI click on "Sign in & security", choose "email address", type the new email and password, but the change does not stick.
Ok, I have more information.
I was able to change the email using Safari on iOS. I could not get the form to work using Safari on MacOS or Chrome for MacOS.
This is a bug that should be reported to Intuit Web Developers.