Hello @Amy B1,

Let me help share information about how the sales order affects the quantity of your inventory items when creating invoices.

To start with, I did try to recreate your scenario base on your initial post when joining this thread. The reason why your inventory items still have the same quantity is the purchase order and bill you created.

When you create a purchase order and copy it to a bill from a sales order, it already added to the quantity of your inventory items. So when you create an invoice from the sales order (associated with a purchase order then a bill) this was the quantity of your inventory items that were sold to your customer.

If you wish to connect with us, you can do so y following the steps below:

1. Go to Help.
2. Select QuickBooks Desktop Help.
3. Click Contact Us.
4. On the new window, select Search something else.
5. Enter a few description of your concern in the Tell us more about your question: field.
6. Select Search.
7. Click Message an Agent.

Additionally, I've also included this helpful reference for a compilation of articles you can use for the year-end preparations: How you can prepare for the 2020 tax season?

If there's anything else that I can help you with, please let me know by leaving any comments below. I'll be here to lend a hand.