I'll provide steps in managing your purchase orders and expenses, Vero2022.

We can only convert purchase orders to bills. Invoices need to be manually created based on the purchase order. 

If these are expenses you incur on behalf of the customer's project, you'll need to create a purchase order then convert it to bill( make sure it's billable). Then, create an invoice and add the billable charges. Here's how:

Create a purchase order

1. Click + New and then select Purchase order.
2. From the Vendor ▼ dropdown, choose the vendor name
3. Complete all the fields, and then click Save and close.

Link purchase order to a bill

1. Select + New, then choose Bill.
2. From the Payee ▼ dropdown, select the vendor. This opens a window with their open purchase orders.
3. Select Add for the correct purchase order. This adds the items from the purchase order. They appear in the Item details section.
4. Tick the Billable checkbox. Then add the customer you plan to bill in the Customer column.
5. Hit Save and close.

Create an invoice and add the billable charges

1. Select + New.
2. Select Invoice.
3. In the Customer ▼ dropdown menu, select the customer you created a billable expense for. This opens the Add to invoice window.
4. Select Add on the billable expense you want to charge to your customer.
5. Select Save and close.

Additionally, here's an article you can check out to help you give your customers detailed reminders about upcoming deadlines: Create and send customer statements in QuickBooks Online.

Drop a comment below if you have further questions about managing your purchase orders and expenses. I'll be here to help. Have a nice day ahead!