You can provide option to the user to change the default language of the application. When the user chooses a new language, please call the below API to persist the new preference.
var json = {};
json.id = "setUserPrefs";
json.callBack = setPrefCallback;
json.userprefs = {"LANGUAGE":"TAMIL"};
apz.ns.setUserPrefs(json)
Subsequently, the application launches in the new language provided it is build with that language. The current language can be accessed using the variable apz.language.