Available in Sage 50 Premium Accounting and higher.

Change Your Inventory Costing Method

To switch between Average Cost and FIFO:

In the Home window, on the Setup Menu, select Settings. Open Inventory & Services, and select Options.
In the Inventory Costing Method section, select either Average or First In, First Out (FIFO).
Click OK.

Note: If you want to use the specific costing method, you must turn on serialized inventory. Specific cost is only used for items with serial numbers. FIFO will be used to track costing for all other inventory items. (Sage 50 Quantum Accounting)

What do you want to do?

Turn on serialized inventory (Sage 50 Quantum Accounting)