Hi there, @ljtaylorsale.

Build Assembly transactions will post to COGS if the item/s in the BOM of the assembly item asset to post on COGS. Also, take note that updating the posting account will not change the previously created transactions. Check with your accountant to know how to create the adjusting entries to fix your books.

On top of that, you can read this article to learn more about the average cost of your items in the last section of this article: Understanding inventory assets and cost of goods sold tracking.

Additionally, I've got you this helpful article for guidance in preparation for the 2020 tax season: QuickBooks Desktop Year-end Checklist.

I'm always around ready to help if you some clarifications regarding this. Just click the Reply button so I can get to you right away. Take care