... A for SetB for Up,12 hours and 24-hour system switchingC for Down ,AlarmD for Exit Time Adjustment 1 ... not be adjusted. 2, 12 hours and 24-hour system switchingIn normal condition,Pls press UP for 3 seconds to ... alarmB,The setting of alarm,In normal condition,Pls press C key ,the ALARM light is on.IF IT is ... setting.If u need more group alarm,pls press C to set the following alarm. Wall LED digital clock