There are lots of settings on your computer that can affect your volume. Here are some questions that will help us diagnose the issue:
1) Is there a problem with sound on other YouTube videos? Try this direct link and then watch other related videos https://youtu.be/QDVxxQOINTM
2) Can you hear other sounds on your computer, such as playing music, or other system sounds?
If the problem is only with videos, check the volume on YouTube. Make sure it isn't muted:
For other sound problems on Windows 10, refer to this help document: https://support.microsoft.com/en-in/help/4026994/windows-10-fix-sound-problems