Okay! I'll give it my best shooootttt
To start off with, On my laptop your YouTube banner doesn't fit properly, the top of the text is cut off, and it also seems to be a little blurry. On mobile it's not as blurry but it's still cut off, by a lot!
Also, I think 'A YouTube Channel' under your name on your banner isn't 100% needed, you could have your timetable, what kind of videos you post ect. UNLESS that's a specific thing on your channel, like an inside joke, I'm not sure
Your thumbnails, I really like the Day 2 Disney Vlog thumbail, it's totally obvious whats going on and the text is very readable, On some of your other thumbnails (like the day 1 vlog or the Snapple fact of the day), the text isn't as readable, i'd suggest a bolder font or trying to make your text bigger. Also your use of the same thumbnails on multiple videos (The snapple ones) might be a little confusing!
I just had a look at your most recent video and it looks really good! Your quality looks really good, the pace of the video is good too
I'd also suggest you make some playlists of your videos so people can click them to watch a whole set of videos from the same type/ set of vlogs ect
Phew, Sorry if that came across as me being picky! hahaha
I hope I helped!!