Thanks for joining into this thread, @Survey2010.

I'm here to help share some steps on how you can print the Project number on your invoices in QuickBooks Desktop. 

At this time, being able to enter or print the Project information on your invoices is currently unavailable in QuickBooks Desktop. However, I can share with you a workaround that can help you achieve your goal. 

You may use the Ship To section on your invoice to hold your Projects' information. You can do this by editing your jobs information and customizing your template.

Let me guide you how:

1. Click on Customer at the top menu bar.
2. Choose a current Job from the Customers & Job list.
3. You can Edit the Job by double-clicking it.
4. On the Address Info tab, check if there is any information under the Ship To section. If there's isn't you can Add New.
5. If you click on Add New, you can enter the Job Details in this section. (Please see the sample screenshots below)
6. Be sure to check the option for the default shipping address, and click the OK button to save the information.  

Once done, You can now start editing your invoice template.

To do that:

1. Click on List at the top menu bar.
2. Select on Templates.
3. Select on the Templates that you wanted to use.
4. Click on the Additional Customization.
5. On the Header tab, put a check-mark on the Ship To section and change the Title to Project Information.
6. Click on OK to save changes.

From there, you can now enter and print the project information on your invoices. 

Also, here are some articles that you can check out about customizing templates in QuickBooks Desktop for your future reference:

• Use and customize form templates.
• Customize email templates in QuickBooks.

On the other hand, I want to ensure that you'll be updated to the most recent product improvements that would be beneficial for you and your business. I'd encourage you to visit the What's New section on your QuickBooks to check out our updates.

You can access it by clicking on the Help menu, hit on New Features and select What's New.

This information should help you print your project number on invoices.

Please let me know if you have any other questions about QuickBooks by leaving a reply below. I'll be around to help you out. Have a great day ahead.