After a long search of how to change the time sig in the middle of the project in Cubase Elements 9, I found nothing. Tons of info for previous versions, which even info for Cubase 8 didn’t help. I just stumbled around Cubase until I found it.
How to do it:
In the Temp Track (CTRL+T in windows), there is a space below the bar numbers. At the very beginning, you’ll see the beginning time signature (4/4 by default). With the Draw Tool, click under any bar, and it will add a time signature at that bar. This new time signature is applied from that bar to the end of the project.
Now to find out the advanced stuff, like correctly transposed polyrhythms.