Great question! There are a few extra steps to change the community email.
- follow the steps in this post to change the admin account for the hub (create new account for the new email address)
- Log in the community with old account
- Select Preferences from the upper right menu

4. Select the gear icon as pictured below to change the email address

- Follow the instructions to change the email address
The next time you need to log in, you will need to use the new account credentials.