No sound to videos
Assuming the volume of your computer speakers (or tablet/phone) is turned up (you can test this by watching a video on YouTube or playing music), then you probably need to turn up the volume on the actual videos. To do this look in the bottom right of the videos. You’ll see 5 little vertical bars. This is the volume control. Drag your cursor over them to make sure all 5 are white – this turns the volume right up.