Is there a way to change the format of the invoice so I can use window envelopes to send hard copies ?

Good evening, @bigktrucking.

At this time, there's not a way to change the format of the Invoice in QuickBooks Self-Employed. I'm going to submit feedback to our Product Development Team about bringing in a feature that will allow this to happen. In the meantime, here's a couple of Community Articles that you may find helpful:

• Add your Company Logo to your Invoices
• How to Print an Invoice

Let me know if you have additional questions or concerns. Have a beautiful day!