Does this help?

How Do I Reset My Child's Password?
Updated 2013-05-23 11:57:01
To use your Parent Account to change your child’s password:

1)    Login to your Parent Account
2)    Click on the name of the child whose password you would like to change
3)    Click on the link on the left to manage your child’s account
4)    From the “Manage Account” screen, select the option to “Change Child’s Password
5)    Enter and Re-enter a new password for your child and click “Change