Ya know, i kinda remember this from way back when. I never did figure it out. I remember wondering why anyone would make a tutorial to show me how sometimes you just can't do what you want.
It won't work, and you have my permission to move on.
Just wait untill you get stuck on a turntable, that sucks. And another hint, when you are at a session that has a red signal that never turns green and ends the session when you pass it and you try forever to get it to change and it never does - give up on that one too(you will be driving a blue UK loco expecting a great fun passenger run when this happens).
Anyway, more fun to be had when you skip it. The tutorials are not so good anyway.