How do I activate and deactivate the childproof lock?

To activate the childproof lock after the programme starts, touch and hold the E (3s) button for 3 seconds until the E (3s) indicator lamp lights up. To deactivate it, touch and hold the E (3s) button again until the indicator lamp turns off. When the childproof lock is active and a button is touched, the E (3s) button will flash as a reminder. (Page 39)