By default Evolution uses the system-wide time zone. This can be changed under EditPreferences Calendar and TasksGeneralTime Time zone.

If you deal a lot with people in another specific time zone you can display that second time zone in the day view of the calendar. You can set a second time zone under EditPreferences Calendar and TasksGeneralTime Second zone.

You can also configure time zone information specific to each appointment. To do that, add a new or edit an existing appointment. Under Time zone, click Select… to customize the time zone. For example, if you live in New York but have a telephone meeting set with someone in California, you need to make sure that your schedules are coordinated. Setting time zones on a per-appointment basis helps avoid that potential confusion.