I can help you with that, willem1.

You can create a custom field for the order number of your invoices. Here's how to do it:

1. Go to the Gear icon.
2. Select Custom fields, then choose Add field.
3. Enter "Order Number" in the Name field.
4. Tick the All Sales forms checkbox.
5. If you want the custom field to appear on printed and delivered forms, turn on the Print on form option.
6. When you're done, click Save.

Additionally, I've added some resources that you can browse to help design your sales forms so your customers will recognize your brand:

• Customize invoices, quotes, and sales receipts
• Add, customize, or remove logos on sales forms

I'm only a few clicks away if you need further assistance with your other QuickBooks tasks. Have a pleasant day ahead.