How do I set default notifications for tasks and appointments?

When you create the appointment, you can choose a reminder option under the reminder section.

You can also set this as a default option which will apply to any new appointment you create. To do this, choose Daylite > Preferences > Notifications > Appointments. Then select Message with Sound from the little drop-down options.

Check the boxes to apply default reminders to new tasks and appointments you create and to items received through delegation or invitation.