Tap on the task for which you want to set a reminder. Beneath it, you'll find . Tap this and 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 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.
Please note: when you are adding a new task, you can set a reminder before you even finish entering the task! When you are typing the new task, you can tap on the icon and select a custom time for your reminder. Any tasks that are added without a specific reminder date will be automatically added to your "Upcoming" category with a reminder for three days from now. If you wish for tasks to be added to the "Today" category, you can simply add them by choosing the + icon next to the today category.
Premium users can also set a location reminder both while adding a task and once it is has already been added.