Thanks for your post.
After marking the Purchase Order as "Received", your stock will be updated automatically.
In the image you added, the stock of this item will increase to 1.
If you need to change the purchase price of a product only for this PO, click the edit icon and then enter a new purchase price in the Total column. This won't be changed in your Product Data.
Meanwhile, if you need to set a new purchase price for the item, you can do so by clicking the "Set Purchase Price" button. This will change the Purchase Price in your Product Data.
I'll leave you here the documentation that explains how to set the purchase price, and here is the tutorial about completing Purchase Order.