Why does QBO 'close' a purchase order that still has an open balance?!

I appreciate you dropping by the Community, @MLH114. 

I'd be happy to help you with your concern. Let me provide you with some insights about the purchase order status.

QuickBooks will automatically close the purchase order, regardless of the remaining balance, when you add a purchase order to an expense or a bill. However, by following the steps below, you may open its status again.

Here's how:

1. Go to Bookkeeping, then Transactions.
2. Select Expenses and choose the purchase order you want to edit.
3. Under the Vendor ▼ dropdown, select the dropdown that says Closed.
4. Change the status to Open.
5. Click Save.

This would do the trick. You can now see the status of your purchase order as Open.

Furthermore, I'm adding this article for your guidance in sending a purchase order: Create and send purchase orders in QuickBooks Online.

Let me know how it goes by dropping a reply below. Have a good one!