You can import your custom invoice template directly from the Custom Form Styles page. I'm here to help you accomplish this.
First off, you'll have to turn the Import Style feature from the QuickBooks Labs page so you can import your custom invoice template. Let me show you how:
Go to the Gear icon.
Under Your Company, select QuickBooks Labs.
Toggle the Import Style feature to turn it on.
Click Done.
Once completed, here's how you can import your custom invoice template:
Go to the Gear icon.
Under Your Company, select Custom Form Styles.
On the New Style menu, select Import Style.
Select Invoice as the type of your form.
Find and upload your custom invoice template.
Match your custom invoice fields according to the QuickBooks fields.