Unlike "Receive" and "Damage" buttons on the Inventory tab, "Actual" allows you to adjust the item quantity without affecting the sales data on the reports.
To adjust inventory item data, navigate to the Management Console's Inventory tab and make sure that option is enabled on the top-right corner of the page, which will reveal additional options for each item, one of them being "Actual":
Press the "Actual" button and a prompt will appear asking you to specify a new quantity and an optional attribute to "Adjust Cost" (based on the new quantity). You can also leave a remark:
Press "Set Actual" to finish the change.
Depending if it was made on an ingredient or product, all the adjustments made are logged to Reports --> Other Reports --> Product/Ingredient Inventory Log. Make sure the view filter there is set to "adjustment":