To set up reminders for multiple days before an event in Microsoft calendar:

1. In Microsoft Calendar, click the New button to create an event.
2. Enter the date, time, and other details for the event.
3. Click the Reminder button.
4. Edit the date and time settings to customize the reminder for multiple days before the event.
5. Select Done once all the settings have been selected.
6. Select Save to save the event and reminder in the Microsoft Calendar.