I suggest you read about namespaces at
You have to read the article about delay procedures in the Waiting and Timing FAQ.
The short answer is to use well named Clock Timers for different delay contexts.
From what I saw in Level1, your close screen technique is inconsistent in different if/then branches. I personally prefer to work only in 1 screen, to avoid screen switching problems.
I have barely looked at your app.
I notice in Level1 you have 3 Canvases, each with 10 Balls.
That tells me that you are not reusing the components, leading to bloated memory use.
Learn to use lists of components and how to represent your game levels in a file.
Sample apps: