Inventory not updating

[katiejs]

We are having a lot of trouble with our inventory keeping correctly. I feel as though all of my settings are correct, but every now and then we sell things online that we do not have in stock, and the inventory totals are way off. The "track quantity" box is checked on every single item, but we still find items in our system that are out of stock, even though Shopify says we have 2 or 4 in stock.