Stock level is not tracked or dependent on the stock level of composites. This is typically used for products that are made up of several other ones. For example you can create a stock item composition titles “Basket of goodies”, add composites Goodie 1 and Goodie 2. You don’t actually stock Basket of Goodies in stock as a physical product, instead you stock Goodie 1 and Goodie 2 as separate items (you might also be selling Goodie 1 and 2 as a separate product or a composite of another product). Therefore Basket of Goodies should be set to not tracked - resulting in the stock level for this product is a minimum stock level of Goodie 1 and Goodie 2.
To set the product as Not Tracked go to My Inventory, find the product that you want to set as Not Tracked and click on the Tracked column to set it to not tracked.
If the stock item has been set to Not Tracked then the in orders total will be displayed as zero. For Composites this is due to the fact that the order has already been recorded against the level of the granular items that make up the composite.