Inventory item's syncronization with that of Purchase/s

Is it possible for the items on purchase/sales invoice to automatically update quantity after every sales and purchase?
If yes, then how do I add prices and quantities to inventory items?

You create an inventory item in the inventory items tab. Set the purchase price and the sale price. Then when you buy (purchase invoice) you select the items that you want to buy using inventory on hand account and select the quantity. Then save that. Then you have increased your inventory quantity.

When you sell, you select sales of inventory account and then select the inventory item. Then your stock will decrease.

When the price changes just go back into inventory item and change your prices there. This won’t affect past purchases and sales.

This, your suggestion, worked perfectly well, and I think I’m back on track…
Thanks a bunch…!