Can I format the additional custom fields available when creating my invoice templates?

Hi there, andrew18. 

Aside from the custom fields, you can use the Message on invoice field to enter the details you want to add. 

Also, you have the option to import your custom form styles for invoices. You'll have to turn this feature on first before importing: Import custom form styles for invoices or estimates. 

Here's how to turn on: 

1. Click the Gear icon at the upper right corner. 
2. Select QuickBooks Labs under the Your Company section. 
3. Click the button to turn on Import Style. 
4. Then, click Done. 

You'll also want to check this article for more details on how to customise invoices, estimates and sales receipts. 

Let me know if you have additional concern. I'm here to help!