My state select water heater does not shut off until I turn the switch off how do I reset the water heater? It seems to occur if the gas has been cut off.

Why do you turn the gas off?seems like if that caused a problem,just don`t turn the gas off ,and then everything will be OK

Thank you, but this does not help me in terms of resetting the thermostat so it will automatically turn on and off when temp. has been reached
Thanks