Scratching animation problem

Hello, I want to make something similar to scratching animation but I have a small problem which as a beginner I can’t beat. So I want my character scratches its head and back to the start pose but it’s just raising its hand and moving to the start pose. Can you explain me why it occurs and what I should do to make this short scene smooth like in the first stage of the video?

Click the little arrow to the left of the action to open up all its channels. There are keyframes in there that you can’t see.

Okay, thanks I saw it earlier but didn’t know what should I do. Now I understand that