Problem with average cost

Welcome to QuickBooks Community, amyn. 

I understand the importance of recording the correct average cost of the 552 items. Let me share some steps to help you fix the discrepancies and reflect the right amount.

We can start by running the Inventory Valuation Summary report to see how QuickBooks got the item's average cost. It will help you locate the cause of the issue. I'll show you how:

1. Select Reports, then click Inventory.
2. Choose Inventory Valuation Summary, then set the dates to All.
3. Double-click the item in question.

Unlocking the average cost to change it is unavailable. What we can do is create an adjustment to these items. To proceed, follow the steps below:

1. Go to the Lists menu and select Item List.
2. Click the Activities drop-down, then pick Adjust Quantity/Value on Hand. 
3. Input the correct details and check the Item Info After Adjustment at the bottom-left of the window.
4. Hit Save & Close.

Here's an article about computing the average cost and handling inventory management: Understand Inventory Assets and COGS tracking.

Find out more about inventory quantities and value through the following resources:

• Average Costing vs FIFO: What’s the best way to analyze inventory costs?
• Adjust your inventory quantity or value in QuickBooks Desktop

I want to make sure I've got you covered. Feel free to click the Reply button below for follow-up questions and clarifications about inventories. I'll be in touch.

@amynhemani 

I suspect there is negative inventories. Run Verify/Rebuild Data utility. Did you encounter any error message?