The Scheduler displays appointments according to the client machine's time zone. If you want to override client settings, use the timeZone option.
You can specify different time zones for an individual appointment. To do this, use the startDateTimeZone and endDateTimeZone options in the appointment's data object. When the Scheduler positions appointments in the timetable, it sums up the offsets of individual time zones and the Scheduler's time zone. Users can view and edit individual time zones in the appointment details form if you enable the editing.allowTimeZoneEditing option.