Allow me to jump in on this thread, @waxglass2020.

As my colleague mentioned, you'll have to create a new item list for your Product Testing. On the Income Account field, select the Product Testing account you created. Also, for the Zero invoice, you'll have to enter the quantity but put zero on the amount field. This helps reduce the inventory and increase the expense account used in tracking your product testing.

Additionally, feel free to visit our Help articles page if you have other QuickBooks concerns, such as setting up advanced reports, online banking, managing reconciliation, transactions, import and export data lists, etc.

I'm always here to help if you have any other concerns. I'll get back to you as soon as I can. Take care always.