... centre button, it will show battery voltage, for example, 3.7V will display “3.7U” .Lock protection: Press "-" and "+" button at the same ... "+" to choose the setting mode: "1.dR"-Display resistance, "2.dU"-Display Voltage,"3.dP"-Display wattage. After that press the big button or ... 3V~6V,with 0.1 volt increments, for example, 3.7V will display “3.7U”. then press the big button again or wait ...