I understand how you want to update the cost automatically while using the assembly items, ChrisK23.

In QuickBooks Desktop, you need to manually update the cost of each item. You can use the Add/Edit Multiple List Entries option to edit the cost and price of your items.

If you have an Excel file, you can copy the data from there, then paste it into the Add/Edit Multiple List Entries window to expedite the process. I'll show you how:

1. Select List from the top menu bar, then choose Add/Edit Multiple List Entries.
2. Click the List drop-down arrow, then select the list that you want to update.
3. Choose in any field and begin making changes.
4. You can copy (Ctrl+C) the data from Excel then paste (Ctrl+V) it into the Add/Edit Multiple List Entries window.
5. To copy the data in a specific field to the remaining records, simply highlight the desired field and right click then choose Copy Down. If data is in any of those remaining fields, it will be overwritten.
6. To duplicate a row simply place your cursor in any row, right-click and choose Duplicate Row. The record is duplicated into the next row and is preceded with the word "DUP."
7. Click Save Changes when you're done.

Learn more about tracking products you manufacture through this link: Combine your inventory items to build finished goods.

Please get back to me if you require more information about this. I'd be more than willing to provide additional assistance. Have a good one and stay safe!