Idk how to find composer names and copyright information for this song:
Can anybody help me and/or tell me how I can find this info(for any song I mean, is there a list somewhere or something?)
Also it says in the description of the video that the composer is TBA but I don't know who or what that is and I'm not really sure so if anyone can clarify that for me, that'd be great.
For future reference, VGMdb (http://vgmdb.net/) is your best bet for accuracy.
Also when he says TBA, it's just short for "to be announced," meaning the youtube video creator has no idea who it is either.
For this song, I found an article on Kotaku and the writer apparently contacted Nintendo to figure out who composes the menu music:
"I asked the folks at Nintendo if they could get me the name of the composer behind this music, but they weren't able to get the information."
So yah. Unfortunately it's hard to get this stuff for menu themes. Wait and see if anyone else can help you find this, otherwise I would just ask Deku what he thinks about it.