The time zone of the configuration (Start and End time)
When creating or editing a Countdown Timer Bar, the app always shows you your computer/browser's timezone. So if you live in EST and you create a bar, the time-zone you set for that bar's configuration will be EST. If someone else (say, a colleague) who lives in a different time-zone tries to edit your bar, they will see it configured based on their time-zone.
If you want to configure the bar based on a different timezone from your own, you can simply adjust the time accordingly. So if you want to show the bar at Starting on November 1st at 3PM PST but you live in EST (3 hours ahead), you would target 6pm.
The time zone of the daily countdown (if using Type C)
If you set the bar to display from 9AM-5PM every day, the bar will show when your customer's time-zone reaches 9AM-5PM. This timer uses the visitor's computers time to set the timer.