If you're having trouble turning subtitles off, please try the following:

1. Go to your device's home screen.
2. Open the TV app.
3. Tap into any video in the app that has subtitles.
4. Tap the screen (so that the pause/play button, fast forward button, etc. show).
5. Tap on the speech bubble in the bottom right hand corner.
6. Tap on English to untick.

Now when you go back to Tubi TV, any video you play will have the subtitles off.

If subtitles on Tubi TV videos still won't turn off, please reference this article: How to turn subtitles on and off?