I want to link several line items on a bill to one PO but it will only let me link the first line.

Good to see you here in the Community, @nancy-casselman.

In QuickBooks Online (QBO) you'll need first to create Purchase Order and then link it to a Bill so you can make payment. You can only copy a purchase order to a bill. To attach a PO to a bill, please refer to the steps below:

1. From QuickBooks Online, click the Plus (+) icon and select Bill. 
2. Select the Vendor whose purchase order you're adding in the dropdown menu at the top.
3. On the right side of the screen, an Add to Bill sidebar will appear listing their open transactions. Select Add For the PO you'd like to convert. 
4. Fill out the rest of the transaction form as needed, then click Save and close.

You can access, export, or print your purchase order report so you have a copy on hand. You may also use this to see those open purchase orders and to review the purchase orders created within a specific period. 

Please keep in touch with me here if you have any additional questions about bills and purchase orders in QBO. I'm always around to help. Thanks for coming to the Community, keep safe.

I have a PO with multiple lines but I need to create a bill only for the first line. How do I do that? And leave the remaining lines for future bills.

Hello there, @Etty.

Once you've created the PO, you'll have to click the Copy to Bill button on the Purchase Order window.

When copied onn the Bill window, there you'll see the option to remove the order or line items by clicking the mini Trash can icon. Then click Save and close to record the bill.

To find out more on how purchase order works in QuickBooks, you can refer to this article: Create purchase orders in QuickBooks Online. It includes how to receive or pay part of a purchase order.

In case you wanted to run PO reports, you can utilize the Search icon on the upper right and then type one of these statements:

• Open Purchase Order List
• Open Purchase Order Detail
• Purchases by Product/Service Detail
• Purchases by Vendor Detail

Additionally, you can reference this article for the detailed steps when entering bill payments: Enter and pay bills.

Please let me know if you have more questions in mind. I'll wait for your reply. Have a great day!