For both iPhones and Android phones

1. Open the Google Home app.

2. Click your personal icon in the lower right corner. 

3. At the bottom of the Google Assistant heading, tap More settings.

4. Tap Assistant in the menu bar at the top. 

5. Tap Voice Match > Teach your Assistant your voice again.

6. When a popup asks if you'd like to Cancel or Retrain, choose Retrain.

7. Follow the requests to speak to repeat the training phrases.