To change your email address, you first need to verify your account. Your account can be verified by going to 'Edit Profile', then scroll down to the 'Manage Login Email' section, where you can verify your account.
Click 'Request Verification Link', and an email with the verification link will be sent. Open the link in the email to verify your account.
Once this is done, you will be able to change your email address. Go to 'Edit Profile' again, and scroll down to the 'Manage Login Email'. Click 'Change Login Email', and you will then be asked to type in your new email address in the text box.
A verification email will be sent to your new email address. Opening the link in the email will update your email login. You can then login using your new email address and your usual password.