In this setting, you set up the Countdown timezone: Select the time zone you want the countdown to be displayed in.
This option will be applied to all countdown on the theme such as: countdown section, product countdown
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There are 2 options for you to choose from: Shop timezone and Users local time zone
Shop timezone: It takes from your store time zone in Shopify Settings
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Users local time zone: It shows the countdown in customer's time zone.