Hi hugh-dunlop-gmai,
Being able to add your own personal touch to an invoice is a great way to customize your customers experience. I can help go over how to customize your invoice to include details.
In the QuickBooks Self-Employed edition you can customize your invoice to include your payment details and a message to your customers. You can use the message section on the create invoice screen to include the details you wish to add. For more customization options you can also look into upgrading your account to QuickBooks Online and get the ability to upload your own invoice template or customize an existing one. You can switch to QuickBooks Online by following this article.
If you do decide to switch to QuickBooks Online you can go over this article to walk you through how to import your custom template and here to customize existing templates.
Hope this helps!
