Hey Yushi,
One thing that you could definitely improve on and wouldn't take much work, is your thumbnails. It is difficult to see the writing on most of them, on some you have used images that have been either cropped badly or expanded, which just does not look appealing unfortunately. I think that if you were able to just spend a few more minutes on them, that would greatly improve your channel.
Content wise, you cover a lot of different topics, which even though it is counterintuitive, it can make it more difficult for YouTube to make you show up in searches, as it usually prefers channels which stick to one or two things, but you are obviously not doing too bad, but just maybe give a thought to it and really decide what you would want to do with your channel. If this is it, then keep going and make it great
I hope that helps. Best of luck with your channel.
Valerik