Localization at the Server and Application level
Selecting your server's default localization settings
In SiteAdmin you can specify which will be the default settings for all your applications and server.
If you set a localization at your server level, it means all the new applications you create, will have that localization settings by default.
Go to Settings > Localization and specify your Time Zone, Language, etc.
Note that you can also set the default language and Address format for your Geocoder in this screen too.
Localization settings per application
The localization settings can also be modified at the application level. This means that each of your customers could have a different localization settings if needed. This could be useful if you have customers in different countries or time zones.
To change this setting, click in your application name
Now edit the Localization settings for your application under Localization category
Finish by clicking in Save.
Note: changing the localization settings per application will apply those settings to all users of that application. Is not possible to have different time zones, units of measurement, culture, etc per user. Only the language could be set per user.