You must select an account for this transaction. What does this mean while creating a PO

Welcome to QuickBooks Community, accounts-zuddl-c.

Let me help you in creating a purchase order.

QuickBooks Online allows you to use the Category details or Item details when adding items to purchase orders. The difference is that the Category details section requires you to select an account or category while the Item details need you to add the product itself.

It could be that you choose the Category details section, then entered info, but forgot to select an account. This causes the said error. Here's how it looks like:

Make sure you enter all required details needed before saving it. I also suggest using the Item details section instead. If you need help on how to create one, please check this link: Create and send purchase orders in QuickBooks Online. This link also shows you how to copy PO to expenses or bills.

Leave a comment here if you need more assistance. Take care!