TCL P608FLW - Washing Machine Functions; Understanding Indicator Lights; Washing Program Descriptions

Press the "Speed" and "Delay" button simultaneously for 3 seconds after
the wash cycle has started to activate or deactivate the "Sound Off" function.
Press the "Temp" and "Speed" button simultaneously for 3 seconds after
the wash cycle has started to activate or deactivate the "Child Lock" function.