When Item crafting, you cannot set the number of Advantages, only Threats, Successes, Triumphs and Despairs.
Use the radio buttons to choose either advantage or threat for the first numeric control. Default is advantage.
Oh, and when crafting a droid, each template selection (chassis or directive) has its own set of symbols, so if you're adding a directive as well as a chassis, you'll need to enter your roll results twice.