Your Voter Account Identifier is your email address.
If you go into your Voter Account and change the data associated with your email address, this will not create a new Voter Account for someone else, but rather will update the data associated with your account.
If you go into your Voter Account and change the email address, your previous Voter Account Email Identifier will be changed to the new email address.
Remember: One Voter Account per email address per voter. Be sure to log out of your Voter Account when you are finished using it.