Email field replaced with username when editing profile

Whenever I edit my profile with an iphone or ipad, either through the Joomla back end, or the front-end profile Edit page, the email field is automatically replaced with the username. This happens in Chrome and Safari, but not in Firefox..

Seems like this happens because the user signs in to the email/username field using a username, the browser then automatically saves the username and when the profile is edited, the browser automatically fills in the email field with the saved username.

Any way I can stop this happening? Can we change the log-in field name to something other than email? If I set it so that users can use usernames only, users who forget their username will then have to go through the whole password reset process..

It's browser auto complete. Your device or browser is responsible for it doing that. There is no way to stop it other than turn off auto complete in your device or browser for your site if possible. Adding autocomplete="off" to the input may help, but usually it just gets ignored however you can't currently set this on fields and is only set for password fields at this time (we've a feature ticket to extend the autocomplete="off" to other fields already).