I've never been able to see these things. In this example, I always see two squares when trying to look behind it, never 4 like the instructions require. How

I've never been able to see these things. In this example, I always see two squares when trying to look behind it, never 4 like the instructions require. How can I let my eyes focus behind the screen? I can focus my eyes in front of it by looking at my finger, and get 4 squares that way, but that doesn't work for focusing behind it, for me. No planet appears when making it 3 squares while looking at finger in front of it either for me. And if I remove my finger, my eyes immediately change their focus :/ Any tips?