Catalina 10.15 > How to stop right sliding between programs?

exactly the same issue on Catalina 10.15...absolutely stupid, ridiculous and annoying feature..i am not quite sure whether i click on something or it came out of blue...please help...

Momarch

Mac Mojave 10.14.6 How to stop right sliding between programs?

When i move from program to program, example chrome to excel the existing window slides off to the right. This is fairly new, must have started during an update. If i click from the bar at the bottom to open something new, instead of just going on top, everything else slides off the page and the new item opens up. How do I stop this?? I need excel and chrome open on the same window so i can copy some numbers and what not....and besides its just annoying. I prefer to have the things on the same window so i can move back and forth between them as needed.