Why wont it let me change my email address associated with my account?

You can check or change the e-mail address on file for you by following the steps in this TurboTax Help article:  How do I change my TurboTax account email?

I followed instructions to change my email address & it still won't let me change it.

@margoneri Once you change your email address, please ensure that you revisit the email section and select the Verify email link.  See the below screenshot for reference.