Let me provide some details about products and services and when recording a bill or purchase order, Accounting.
When creating a purchase order, you can enter the specific items you want to buy and the quantity. Are you trying to say that when you entered your transactions, the quantity was not reflected correctly on the Products and services page?
If so, it's because the correct process is to record a purchase order first and then convert it to a bill. After that, once the bill is converted, this is the time you'll see the number of quantities of the product being added to the Products and services page.
Additionally, to know more about how you can review and manage bills and at the same time monitor their payments, I've added this article for more details: Enter And Manage Bills And Bill Payments In QuickBooks Online.
Reply to a comment below if you need further assistance when making purchase orders or tracking your product and services. I'll be one post away if you need help.