Tap on the task you want to set the reminder for. Underneath, you'll find. Tap it, and then you will be able to set a reminder for a specific date and time, or a daily/weekly/monthly reminder. On a shared task, when you change the task time, the other members will see the same time but each one can decide whether to be reminded or not. Alerts for individual tasks can be toggled ON or OFF by tapping on the task to see the task options, and then tapping on the bell icon to open the reminder settings.