If you want to update any of your registration information, including the email or password you use for Pandora, follow the instructions below:
On the Web:
Sign in to your account on a computer and click here.
Make sure to hit Save changes when you're done.
On the iPhone or iPod:
Launch the Pandora app, tap on Settings, then select ‘Account.’.
When you are finished making changes, be sure to tap ‘Save’ to update your information.