OpenGameArt.org
Cheerful Upbeat Tune
Credit line
"Cheerful Upbeat Tune" by ViRiX licensed CC-BY-SA 3.0: https://opengameart.org/content/cheerful-upbeat-tune Author's attribution notice: This is under the CC license. In the redits, please write: "Some of the songs and/or sound efects in this project were created by ViRiX Dreamcore (David Mckee). www.virixcore.net for more information"
Where to put it: Game credits or video description. If the entry has a "Copyright/Attribution Notice", follow that.