Reminders for different tasks under the same organization.

If I created different tasks under one organization for different dates it reminds me every day for all the tasks.

If I want a reminder for a specific task only for example on the 21st of every month how do I set the reminder for that specific task on that day or the day before?

I have a few tasks under one Organization and the organization settings sets a reminder for all the tasks. How do I set a reminder for a individual sub task.