How do you add an embedded invoice to an email in custom style forms

We appreciate you posting here in the Community, @Rozmore13.

Could you please elaborate on what you mean by embedding an invoice to an email in Custom Form Styles?

It would also be great if you can provide us with a direct link for the ProAdvisor module that you're referring to or share a screenshot of the instruction from the training guide. This will help us verify the issue further.

In the meantime, I recommend you check out this to learn more about how to personalize and add specific info to your sales forms: Customize invoices, estimates, and sales receipts in QuickBooks Online.

Additionally, I'll also add this link where you can search for articles about the company's income and customers in QuickBooks Online (QBO): QBO Sales and Customer's Help Articles.

Feel free to provide us with more details of your concern by adding a reply below. The Community team always has your back. Have a good one.

Hello there, @Rozmore13. I appreciate you getting back and providing a screenshot.

I'm here to ensure you can embed your invoices when emailing your customers through QuickBooks Online (QBO).

To do this, navigate to Account and Settings and choose HTML for the email options for invoices. For detailed steps, here's how:

1. Go to the gear icon at the top.
2. Select Account and settings.
3. In the left menu, choose Sales.
4. Go to the Online delivery section. 
5. Choose HTML under the Additional email options for invoices dropdown menu.
6. Click Save, then Done.

For more details on how you can email sales forms to your customers, here's a great resource that you can read: Email or print multiple sales forms in QuickBooks Online.

For future reference, check out this article to learn how to receive invoice payment in QuickBooks Online. 

If you need anything else, please let me know. I want to help in any way I can.