Thanks for getting back to us, RodWright.

It might be that you're using Tile Horizontally or Tile Vertically as your window type. That is why when you open another tab, the first tab will go back to its original screen. You'll have the option to change your window type.

To choose Cascade as your window type, just go to your WINDOW menu, then select Cascade.

Feel free to reach out to me if I can be of any help. I'm always around to help you.