Most times they do have the permission and sometimes they don't even have to worry about it because their network is responsible for that.But I don't get why so many other youtubers can use copyrighted music without permission. Anyways, thank you guys a lot
Of course, using your own music is the best way^^ But I advise you to write that down in the description so the people know it is your own musicI'd better use my own music :-D
Thank you Math