Studio Operations has more than one email field because your login address and your studio contact address can be different.
The notification address
For studio notifications, Studio Operations first looks for the Studio email saved under Settings → Studio.
If a Studio email is present, notifications are sent there. If it is blank, Studio Operations falls back to the email address on your user account.
Change where notifications go
Update the Studio email when you want inquiry and sale notifications delivered to a dedicated studio inbox. Leave it blank when you want them to follow your account email instead.
This does not change your login
Changing the Studio email does not change the email you use to sign in. Your account email is managed separately under Settings → Account.
This also does not change which notices are turned on
Use Settings → Account for the notification switches themselves. For example, Someone asks about a work controls inquiry emails. See which notification types are actually connected now.