Purchase Orders - Change the sorting order of items from Alphabetical

When I manually add an item to a PO, as soon as I finish typing it, it jumps up to the alphabetical position with the other items, before i select a size or color. So confusing, Especially, if the order already has other PC54 in it, for example, and now i need to add a specific color size, i don't know which line item was the new one to enter my color and size cuz it just mixes in with the others