Where do I add an email for invoicing?

In the account details section, enter the email to billing email for invoices and summaries section. Separate multiple email addresses with a comma. We send overviews in encrypted emails for higher personal data protection. If the email recipient needs access to overviews, make sure they have the password, available in the payments and billing section, or add them as an administrator among the users in the web app.

Where do I add an email for invoicing?