I had similar issues as you had
Sadime, when trying out my bike. I was scooting back also. Didn't know why. it was good reading that i would need a seat adjustment. I'd love to ride along side someone that knows what's going on and what to try.

Even though I looked at the video, when I read you all say shift down, does that mean in the numbers on the right-hand gear?

Which gear do you use more often? Seems you all are referring to the left one. I've always only used the right because I don't know when to shift. When I would shift, I'd use the right one.

so down shifting is making the number larger or smaller on the front or the back?

Sadieme - I do hear what you are trying to say and I don't know what is happening but I understand, the clanking. Something is not catching on the gear thing. What do they call that when the chain is on the thingy? lol. boy do I need to learn parts. If they have a detailed picture of parts, I could talk more sensibly, (I hope at least) lol