You can change the language that is used for captions in windows, on command buttons, and in other UI elements from both the Classic client and the RoleTailored client.
To change the language from the Classic client
In the Classic client, on the Tools menu, click Language.
In the Application Languages window, select the language, and then click OK.
To change the language from the RoleTailored client
In the RoleTailored client, click Microsoft Dynamics NAV, and then click Select Language.
In the Select Language page, select the language, and then click OK.