Different buttons control different water jet heights. By pressing different combinations of buttons, different fountain patterns can be created. During the rehearsal, Walter sets the water jet controlled by the first button to 1 meter, the second button to 2 meters. During the first actual performance, he presses the second button, followed by the first button. During the second actual performance, he presses the first button, followed by the second button. However, during the two actual performances, the water jet heights controlled by the two buttons were swapped due to a malfunction in the control system.