This is not the impression we want you to experience when setting up payment terms in QuickBooks Desktop, Toonces. 

We can run the repair tool to help resolve odd behavior where payment terms are not automatically populating on invoices. Let's create a backup company file first just incase you ever run into problems. We can use your backup to restore your data. Here's how to repair the software: 

1. Restart your computer.
2. Go to the Windows Start menu, and then pick the Control Panel.
3. Tap Programs and Features and then Uninstall a Program.
4. Choose QuickBooks and then Uninstall/Change.
5. Press Continue or Next.
6. Hit Repair and then Next. Note: The repair should start right away, but it may take a while to finish. You can leave it running and come back once it's done.
7. Click Finish when done.
8. Restart your computer to complete the repair.
9. Ensure that your QuickBooks Desktop is updated to the latest release.

If the same thing happens, try opening another sample file to verify if the same error occurs. The process will also help us identify where the problem is stemming from within the system. Here's how:

1. Open QuickBooks Desktop.
2. In the No Company Open window, click the Open a sample file drop-down. 
3. Follow the remaining steps until finish.

If the options work fine, I suggest running the Verify Data and Verify Rebuild tools. These features in QuickBooks will help self-identify data issues within a company file and self-resolve them using Rebuild Data. 

To run Verify Data:

1. Click the File tab at the top menu bar.
2. Hover your cursor to Utilities.
3. Select Verify Data.

Next, please run the Rebuild Data option through these steps:

1. Click the File tab at the top menu bar.
2. Hover your cursor to Utilities.
3. Select Verify Rebuild.

After following the steps above, restart your QuickBooks. Here's an article you can refer to for more details about fixing data damage on your QuickBooks Desktop company file. Visit our QuickBooks Help Articles page for more insight s about managing your business in your software.

I'd like to know how you get on after performing the steps as I want to ensure this is resolved for you. Just reply to this post and I'll get back to you. Take care always.