Stock is kept per kitchen location. When a location is selected in the admin header: type the quantity in the Stock field of the ingredient form and Save, or click the Stock value in the list (or the report's Stock column) and enter the new quantity (in the ingredient's base unit). When no location is selected, the list and form show the total across all locations; click the value (or the Edit link next to the Stock label) to open the Edit Stock pop-up, whose body is titled "Available stock per kitchen location" — enter a quantity per location and click Submit. Quantities below 0 are rejected ("Invalid quantity for Ingredient ID"). You can only edit per-location stock on an ingredient that has already been saved.