Default for sending out email is always the same* which you cannot change it. What you can change is reply-to email address of your own for customers, different than regular company email address.
- *default email address from Intuit[firstname.lastname@example.org]
From the home page screen > company gear (upper right corner) > settings > company > contact info > add customer email (this is where you add email different from the company email address).
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