SCREENSHOT: How to "Adjust Quantity"

To make a change to your inventory, use the Adjust Quantity option at the bottom of the Inventory screen.  Add/subtract Quantity and provide a Reason Code.

(To add a Reason Code, go to the Settings option at the top of the screen and select Adjust Quantity Reason.  Add a Reason name and Save.  The Reason Name will now appear in the Reason Code drop down list.)