Stock Projected Qty

Hi guy,
When I set up the Sales Order, I installed the display of Projected Qty. However, when I sell products through POS, this number appears in the Stock Projected Qty report but does not update in theSales Order.
Could anybody tell me the reason?

@Xu_Mi Assume you have stock of Item A 10pcs.
Now you are making and submitting a delivery note for Item A of 5 pcs . so the Actual Qty as well as the projected qty will be now 5 after deducting the delivered qty.
Then you are making and submitting a Sales order (if reserve stock enabled) for Item A of 2 pcs. Now,
Actual Qty will be 5 and reserved qty will be 2 and Projected qty will be 3 (which is Actual Qty - Reserved Qty).
Then you making a Delivery Note for the sales order (2 pcs). Now
Actual qty will be 3, Reserved Qty → 0 , Projected Qty - 3.
Hope you understand.

I just wonder why the figures on the Stock Projected Qty report don’t match the Projected Qty numbers on the SO