For a few months now, the mobile version of the YouTube app on either iOS or Android has allowed mobile users to easily advance or rewind videos by double-tapping the video window. An inherently useful trick, it makes video navigation as easy as it gets - instead of having to deal with the pesky tiny seek bar, people can simply take advantage of the touch screens at our fingertips.
By default, the YouTube app will advance or rewind the video you're watching by 10 seconds. That's fine for most uses, and it feels like a nice middle ground between "too little" and "too much", but there's always the possibility that you might want to have a stronger say with how much time this gesture will go through.
Luckily, you can do that! Here's how: