You can set default locale, time zone, and character set for the site.
Locale represents a set of user interface properties -- including language and time zone, for example -- that are often related to the user's geographic region. The locale setting determines what language UI default text is displayed in. It also determines how dates are formatted, what the character encoding is, and so on. The correct locale helps to make people's experience in the community feel more familiar and comfortable. For sites that want to support a broad variety of languages, Jive requires using "UTF-8" (Unicode) as your character encoding. For more about this, see Localizing the Application.
Here you can set the server time zone, which dictates the time zone Jive uses for the midnight start time and 11:59 end time for announcements, polls, projects, tasks, and checkpoints. Blog posts obtain their settings from the user's time zone.
Admin Console: System > Management > Locale