For the original song, be sure to credit all of the contributors. This may just be the original producer, but sometimes there are other people involved, such as arrangers, lyricists, guitarists, and so on. You can also link back to the original song.
For the cover that you made, credit those who created whatever resources you made use of. If you're using a premade UST, credit that person. If you're using an instrumental remake instead of the official instrumental, credit that person. If someone else helped you with the tuning or the mixing, credit those people
For a video, if other people helped with the artwork and the video editing, they will need to be credited as well.
Generally, writing the name/alias of the person will be enough to help listeners know who was involved and find their other work. If requested, or if you want to help listeners even more, you may have to include social media links.
That said, if there's a part of the process that you did on your own, you can choose whether or not you want to credit yourself for it. There's an implication that anything WITHOUT credit is a part that you did yourself, so it's more important to specify what parts were due to the work of other people.