How to change the default email address from Apple Calendar?

Hi Marshall Lee,

Thank you for using the Apple Support Communities! To add a Calendar account to your Mac, the steps below can help:

Add or delete calendar accounts on Mac

Add a calendar account

1. In the Calendar app  on your Mac, choose Calendar > Add Account.

2. Do one of the following:

* Select your calendar account provider, click Continue, then follow the onscreen instructions.

* If your calendar account provider isn’t listed, ask your provider for the information you need to enter. 

* Choose Other CalDAV Account, click the Account Type pop-up menu, then choose an option based on the information you need to enter.

* Automatic: Choose this option if you just need to enter your email address and password.

* Manual: Choose this option if you need to enter your user name, password, and the server address.

* Advanced: Choose this option if you need to enter your user name, password, server address, server path and port number. You can also select checkboxes if you need to use SSL or Kerberos v5 authentication.

Each account you add is listed separately in the sidebar. If the sidebar isn’t showing, choose View > Show Calendar List or click the Calendar List button  in the toolbar.

Set up your iOS and iPadOS devices to use the same account, so that your calendars stay up to date across all those devices and your Apple Watch.

Hope this helps!

Have a great day.