To change the language of chat box at your website, enter the Jivochat admin panel and press the Settings button under the name of the web-site.
Then go to the Options.
Chat Window Language is the option where you can choose one of the 21 available languages which the chat box on your website will use. In addition, the Professional Edition you will allow you to edit the text of the translations or add your own translation for the required language.
List of the available languages:
Also please check following settings:
1.The “Design” section > Labels
2.The “Triggers” section, you should change the language for each trigger. Just press the “Configure” button to do this.