Hello there, @Susan1216.

We appreciate you sharing this information and working to find a solution. Let me help add a class to a line item while you're making a purchase order in QuickBooks Desktop (QBDT).

We can add the class in the column by customizing the template. Here's how:

1. Open the purchase order and click the formatting tab.
   
2. Double-click "Custom Purchase Order Template".
   
3. Then, click Additional Customization.
   
4. Tap Columns and put a checkmark on the class if you want to show it on screen or print. Then hit OK.

Once done, we can now see the class on the line item. Please see the screenshot below for visual preferences.

I've attached some articles below for additional reference: 
 

• Use and customize form templates
• Customize reports in QuickBooks Desktop 
   

That should point in the right direction today. Drop me a comment below if you have any other questions about customizing purchase orders or if you have any other questions about QuickBooks. I'll be happy to help you out.