email address cannot be updated in Android App or Firefox on Win10 PC

I've been unable to update my (about to expire) email addressa. In my android phone app: tapping the envelope or email or anything on that line in the account settings does not allow any edit.b. On my Win10 PC using Firefox (and Edge): the update details dialog box doesn't allow my email address to be edited and the save button is greyed-out.Thanks for your help.Mike