Annoying desktop "features"

There are a couple of useless features in the KDE desktop.  One is something triggers a bunch of thumbnail over the desktop, instead of the normal apps & folders.  The other is when the mouse is held over an app, such as a browser, again thumnails pop up along the bottom of the screen, all showing exactly the same thing, so they can't even be used to select an open windows.  I find both of these to not only be useless, but often get in my way.  Is there anyway to disable this nonsense? I'm running Leap 15.2. tnx jk