I've clicked through all the options in the settings and no matter what I click I can't seem to get YouTube videos to play in the boost app. Every time I click on one it opens my YouTube app and I don't know how to get that to stop happening. I'm on a galaxy s22 ultra if that helps.
Just tried it and it still opens in the external YouTube app.
Besides that check says if you uncheck it then it will open youtube in the external youtube app.