Well, if it's for a YT video then you can only use royalty-free songs for example, Jazzy Frenchy or The Elevator Bossa Nova. You can't really use major artist's songs or else you'll get copyright claimed. As long as you give credit to the royalty-free songs you'll be fine.
I don't know what you're using to make a project, but from my point of view if you're making a Scratch project then you can use any song (royalty-free or not) as long as you give credit.
It really just depends on what you're using to make the project and make sure to read the rules on copyright-claimed songs and to make sure that you can use them.