First-time language set: Press the power button to turn on the toothbrush, then press the function button to choose between languages—English, Chinese, or Japanese. Once you've got your preferred language, press the power button to lock it in.Reset the language: Hold the power button for about 8 seconds until you see the system reset icon and progress bar, then let go. From there, you can pick a new language by following the same steps of the first time set.