Hi @petra
When you are playing the lesson video, there is a little square with another smaller square in the bottom, right corner of the parent square. It’s the second from the right, between the “1x” speed control and the “[ ]” full screen control. When you click it, a little window will pop out and you can then go over to your lesson pdf opened in another browser tab. Then you can “grab” the corner of the pop out and make it larger. That way, you can look at the pdf while you are listening to the lesson.
You mention “all three”. I’m not sure what that means. I’m only aware of the 2 screens being opened at the same time.
I hope this helps. Please refine your question if I misunderstood.
MG 😀