You can log in to the Screencastify extension with any Google account. To switch the Google account you're logged in with, follow these steps:
- Open the extension's Main Menu
- Click 'Switch Account'
- Choose the new Google account you'd like to sign in with
You'll then be signed in to Screencastify extension with that account. To confirm, check the email shown at the top of the Main Menu in the Screencastify extension.