I understand the FIFO process but why doesn't removing inventory (taking it to 0) and then changing the unit cost and receiving inventory back in doesn't change the unit cost? If I remove 600 books at $2.49/bk and then change the cost to $5.02 and receive 600 books in the new unit cost should be $5.02. I can't create a new item because all my sales history is tied to this item. We pay royalties on our books some increase by quantity sales

Adding value to the over all inventory is what's being done but I need the unit cost to be correct. Otherwise the inventory value won't balance to the balance sheet.

This is a huge system flaw if you can't correct the unit cost of a product.