I appreciate you for reaching out with the Community, @salliethorn.
Let me help you add a customer to your purchase order transaction in QuickBooks Online. Here's how:
- Click + New icon.
- Under Vendors, select Purchase order.
- In Category details or Items details, you can add your Customer/Project (Please see the screenshot below).
- Click Save and Close.
You can refer to this article for more details: Create and send purchase orders in QuickBooks Online.
I've also added this article that you might find useful in managing the status of your transactions: Add purchase orders to expenses, bills, or checks in QuickBooks Online.
Keep me posted if you have further questions with your purchase orders. I'll make sure to get back to you as soon as I can. Have a great day!