No, it is highly unlikely that playing with the voltage settings of a dishwasher while it is in operation will cause it to shriek loudly or spark at you. Dishwashers are designed with safety features to prevent such situations. Most modern dishwashers are equipped with circuit breakers and other protective mechanisms that would trip or shut off power if there is a voltage surge or other electrical issues.
However, it is important to note that tampering with the electrical components of any appliance, including a dishwasher, can be dangerous and may result in electrical hazards or damage to the appliance. Modifying the voltage settings of a dishwasher is not recommended and should only be done by a qualified professional, if necessary, to ensure it is compatible with your electrical system.
If you are experiencing any issues with your dishwasher, it is best to consult the manufacturer's instructions or contact a professional appliance repair service for assistance.