You have to click the green flag a few times otherwise there will be glitches. Nothing requires dragging. Just click whatever you want to move and it will follow your mouse until you get it to the right place.
I kind of got the idea from the Papa's Games. Like if you've ever played Papa's Bakeria, Cupcakeria, Sushiria, Freezeria, Pizzeria, etc. I really like them so I made something similar. No where near as good. I don't have the patience for drawing, so I know it's not the best... I might add a third costumer later.