Invetory Stock not updated Automatically (URGETNT)

For example , the item’s stock is 1 , after purchase it , the stock number did’t change , it should change to 0 or out of stock but still remain the same.

I resolve the problem, is because I use the test paypal account so that not affect my inventory stock. But when I use the real paypal account and make sure the ” woocomemrce status order” is completed, the stock amount will automatic decrease.