The User Locale setting is used to change the language conventions that will be displayed on an application's user interface. Adding language groups does not automatically change the user's time, date, number, and currency formats. All Western European user locale formats are already available by default. To set the international formats to a User Locale other than Western Europe, you must first add the appropriate LangPacks. After you have installed the LangPack on the system, follow these steps to set the User Locale.
Note that these steps do not require a reboot.