After you create an iTunes Connect record for your app, you can update the record with localized text and images to support additional store territories.
For example, if you created the iTunes Connect record for your app with the default language English, stores in all territories display information for the app in English. If you now upload metadata, keywords, and screenshots in French, users whose language is set to French or who are located in a territory that includes French (and not English) as a supported language see the French metadata instead of the English metadata. Your app is also searchable in all French-language stores by the localized keywords. In other store territories, the default language, in this case English, appears.
Note that the language set for users’ devices controls which metadata is used when an app is presented in the store. If there’s no localized metadata available that matches the current language, the store shows the metadata for the default language. Note, too, that the URL for the app is the same, regardless of the iOS or OS X language setting.
Adding New Languages
When you add a new language, all information except the description and keywords is prepopulated from the default language metadata, including any screenshots. You need to update the metadata with localized information for the new language. If you don’t upload new screenshots, the previous (default language) versions are used.
Viewing Metadata for Supported Languages
From an app’s Version Details page, you can view the metadata and images entered for a specific language. Choose the language from the Activated Languages list in the Choose Another Language menu.
Editing Existing Languages
From an app’s Version Details page, you can edit localizations that you’ve already added. Find the language in the Choose Another Language menu, and click Edit.
If the language doesn’t appear in the Activated Languages list, there’s no metadata entered for the language.
If you’ve added localized metadata for your app but no longer want to manage it, you can delete it from the app version at any time. From an app’s Version Details page, you can delete support for a language. Choose the language from the Choose Another Language menu, and then click Delete in the section heading.
Changing the Default Language
The default language is the language that the store uses to display information for an app when the app doesn’t have localized metadata for a store territory. If you find that your potential users are better served by a different default language, you can change the default language for an app.
To change the default language, you add metadata for the new language and then switch which language is used by default.