Some web apps in ClassLink use self managed passwords. These applications are referred to Password Locker apps. These are the apps that prompted you for your username and or password the first time you used it.
You can follow the directions bellow if you you ever find that you need to update your credentials.
How to update using a web browser.
1. Log into your ClassLink account on the iPad app. from the dashboard, click the menu button in the top left.
2. Click on the settings button on the bottom left.
3. On the settings window make sure you are in the "Password Locker" tab and click on the web app you wish to update on the right.
4. On the web app settings page click the "Default" button.
5. In the Password Locker settings page update your credentials then click the "Save" button.