Hi Anna, thanks for posting the video. So there’s a few things we need to work on. First, make sure you tune your ukulele before playing. When you are fretting a note (regardless of it being a single note or in a chord), you never want to pull the string down. The string should always remain perfectly straight. If you pull it down, it will cause the note to go sharp.
I would also recommend to lighten up your strum attack. Check out this lesson from our Beginner’s Course and Skip to 8:20 in the video lesson. Notice how when I strum down with my index finger, I have a very light touch. This produces a sweet and pleasing tone.
Give these suggestions a shot and let me know how it goes 🙂