To stop pop-up ads or notifications from Google Assistant or Gemini while watching videos, you can disable Google Assistant by opening the Google app, going to Settings, selecting Google Assistant, and toggling it off. Additionally, you can turn off "Hey Google" detection by navigating to Voice Match in the Google app settings and toggling it off. To manage notifications, go to your phone's Settings, select Apps, find Google, and disable its notifications. For Gemini, adjust its permissions and notification settings via the Apps section in Settings, or consider disabling or uninstalling the app causing the interruptions.
