OpenGameArt.org
Cutie Pie
Credit line
"Cutie Pie" by FrancisLeeMusic licensed CC-BY 3.0: https://opengameart.org/content/cutie-pie Author's attribution notice: Head to http://francislee.squarespace.com/services for attribution guidelines.
Where to put it: Game credits or video description. If the entry has a "Copyright/Attribution Notice", follow that.