This is actually a pretty good start. There are a lot of things coming at you for the first time when you get started, and it's difficult to get everything exactly right.
You need to watch these videos several times. Each time you re-watch, you will catch something important that has slipped by you before.
You also need to practice the audio exercises every day, five or six times per week.
Imitate Ken's sound as much as you can. He's showing you the right way to do it. You still need to make your voice a bit brighter and really make it ping. You kind of POP the sound out of the open throat. It's the Lah!!! AHH!!! AHH!!!
It may take you a while to get comfortable with the modifications. You will gradually get the hang of it.
Also, listen carefully to the melodies of the exercises. In a few, your pitch wasn't exactly what Ken had just done. Listen carefully to the notes you are singing and make sure you are singing them back just like Ken did.
In your future demos we need to hear YOUR voice a little better. Ken's voice is just as loud or sometimes louder than your voice on the YouTube video. We need to hear YOU over Ken, so we can help you more with Your voice.
This is a good start. I can see the gears turning in your head as you listen to Ken. You want this to work and that's important. Do your part and we will help you. Listen to Ken. Copy him.
Good job. You're off to a good start!