Hi WHPAV,

From what I'm getting, you're connecting an application to QBO, and for this case, I would recommend posting your question in the Intuit Developers Community. That way, they can work hand-in-hand with you to achieve your goal.

In a happy path's perspective, whatever template (texts, fonts, etc) you set for your quote and invoice, that will be used in your future transactions. See about customizing forms in QBO.

Feel free to reach out if you have other questions.