When you turn on the headphones for the first time, the voice prompts are in English. To select a different language:
Changing the voice prompt language
Press and hold + and - simultaneously until you hear the voice prompt for the first language option
Press + or - to move through the list of languages
When you hear your language, press and hold the Multi-function button to select
Note: You can also change the voice prompt language using the Bose Connect app.