When you try to edit your profile on the Edit Details page on a Microsoft SharePoint Server 2013 site, you cannot change the time zone. The time zone option is disabled.
This issue occurs because the Region setting on the Edit Details page is set to Always use regional settings defined by site administrators.
To resolve this issue, change the Region setting on the Edit Details page to Always use my personal settings. For more information about how to change your region settings on a SharePoint Server 2013 site, go to the following Microsoft website:
Article ID: 2738184 - Last Review: Nov 16, 2012 - Revision: 1
Microsoft SharePoint Server 2013