Trainz

I'm obviously losing it.

After all these years, I still get confused with Layers, Routes and Sessions when it comes to changing and saving the location of the world origin. Whenever I try to change and save it, the origin co-ordinates always end up reverting to what I had before.

Can someone please explain to me, in bullet points, how to set the world origin and save it to both the Route and Session? If that makes sense.