To reschedule a calendar appointment:

1. Go to Calendar in the navigation pane.
2. Find the appointment in your calendar.
3. Double-click on the appointment to open it.
4. Change the start and end time (and date if necessary).
5. Click Save & Close.

You can also change an appointment time by clicking on the appointment in the calendar and dragging it to a new time slot. You can change the length of the appointment by clicking and dragging the top or bottom of the appointment box up or down.