So, pardon the way this might come across, but if you don't have an idea what to do, then whatever editing you've been doing has likely been guided by the wrong reasoning, or perhaps simply "rules" you've read off the internet, regardless of your intentions.
This video does sound good, but what you can do with it will also depend on how it's recorded because it seems to be a piano and vocal recorded together as a single track. You
could make changes, but I guess I'd ask, why? She's done a really nice job, obviously understands how to add a second voice (unless that's someone out of frame!), and the video is posted. On to the next.
While I could think of things I might do, and list them here (others can do that, too, of course), it would be biased, and likely incorrect on some level, because I've never heard your daughter's natural voice, so it's possible it could go the wrong way, and I might also make it worse by simply doing something she'd think was wrong.
So, I'd
start with a conversation with your daughter and whether she wants to improve the audio in her videos, and what things might be bothering her about this, if anything, and you could talk about what you're hearing and come to some agreement about
specifics to address. Then, if you don't know how to make those changes, perhaps come here with a basic audio mix and ask for some suggestions you can try out. Apply the techniques
one at a time, with small moves so you can start to hear which ones are really making the changes you want, and which are simply making changes. We have a tendency to think any change is better (
novelty effect), and that's one of the hardest things to learn to ignore. (Well, I doubt most of us ever learn to completely not be infatuated with our latest whatever, but we learn patience, so perhaps re-listen later or the next day at least
).
Sorry for my [too-typical] long-winded reply that doesn't actually tell you what you asked for.