Provided is a method of setting a system, the method being performed by a processor and including: (a) when receiving detection, by the sensor, of a first amount of goods equal to or larger than a first predetermined amount, displaying, on a display, a first screen prompting setting of a threshold amount of goods corresponding to a condition of trigger output; (b) when the sensor detects reduction of an amount of goods by at least a second predetermined amount after displaying the first screen, acquiring, as the threshold amount, a second amount of reduced goods; (c) after the threshold amount is acquired, displaying, on the display, a second screen for setting an action of the processing device; and (d) based on information on the action set after displaying the second screen, setting output contents to be output by the processing device upon satisfaction of the condition of trigger output.