How Do I Change the Email Address I use for

You can change the email address you use on by going to: 

Your Account > Account Details

Here you can make adjustments in the Email Address field. After you make the change, just remember to click the Save button.

You can also add more email addresses to make sure you never get accidentally locked out of your Account. 

Most people add a work and a personal email or their personal email and another family member's email (your partner, your child, etc.). This provides an important backup in case you lose access to your primary email address (for example, if you change jobs and lose access to your previous work email).