Press the green flag. Wait for however long you want. Then press stop. Doesn't whats happening confuse you so much? Shouldn't nothing happen after you press stop? (Comment your answer to the question!)
This project didn't really take a lot of time. I already had an idea that would blow away people's minds. So what took me the most time was figuring out when the no!!! sprite should show up. 0.3 seconds after stop is pressed or lower? If I had more time and if I wanted to, I would make an actual game instead of the ball changing color. (P.S. Press stop after you press stop to stop the why!) (P.P.S. That was a lot of stops in the P.S)\ (^-^)