Thanks for posting here, @azadehgar,

Can you please share some more details about the problem? Inventory adjustments should not affect created bills, so I will need some more information on what happened and how the adjustment is done.

Any clarification will help me provide the accurate resolution to you.

When you purchase or receive inventory, it debits the Inventory Asset account which is posted in the Balance Sheet report. If there are changes in the quantity because of damages, fire, theft, or breakage, and etc., that's when you use the adjustment option.

The steps and instructions are listed here: Adjust your inventory quantity or value in QuickBooks Desktop

This method affects both the Asset and the COGS account, but not necessarily show a loss in your books. This is because, we are only changing the quantity and asset value of the item, but the average cost of the item remains the same.

If you want to track the loss from damages in the P&L report, you will need to a different entry to account for the unrecoverable funds from damages. This is method is what we call writing off a bad debt. This article can explain the process and steps for you: Write off bad debt in QuickBooks Desktop

I'll be waiting for your response. Connect with me again by clicking the Reply button below. Have a great week ahead!