Let me help share some information about tracking the Cost of Goods Sold.
Inventory COGS is only affected when you sell inventory items on invoices or sales receipts.
When you sell an inventory item, you can run the Transaction Journal Report for the invoice/sales receipt. You will see the Sales/Accounts Receivable transaction and you will see the Inventory/COGS transactions which credit the Inventory Asset account and debits the COGS accounts.
If you've QBO plus plan (or Advanced plan), you can track Cost of Goods Sold (COGS) or Cost of Sales (COS) by CUSTOMER in QuickBooks Online. But you've Essentials or Simple Start, this feature is not available in QBO.
So what's the point of having a P&L report in QBO Simple Start if you cannot enter COGS??? And why in the heck would you leave this out in the first place? I mean its pretty much part of the basics in any business!!
You'll want to enter COGS manually in cash basis when you purchase the item. However, tracking the item when it's sold is unavailable. Let me guide you through the steps.