On the Admin Panel, Configure Site > Social Networking page you can choose to use the Timezone feature, whereby members will be able to choose their timezone on the Edit Profile page.  Set the Server Timezone here - if you are not sure what it is, consult your web hosting provider.

Using the timezone feature can be useful for the date fields on your website, for example for the Comment dates, Messaging dates, or the Public Profile page for the Join date or Last Login date if you are using the Date Format rather than Duration Format.  Then the member can view the dates in their timezone.

Click on the link "choose Date Order/Phases here" to choose the date order and customize date phrases.  The page will open as a page overlay, so you will not lose changes you make on the Configure Site > Social Networking page by clicking on the link.