Lock to Camera trick in one of questions doesn't seem to work in Blender 2.8!
Use workspaces. See the Layout, Modeling, Sculpting, tabs on top?
Right Click Layout and duplicate it, rename to "Quadview". Put the quadview in that tab and single window in the layout tab.
Switch back and fourth between layout and quadview from those tabs so it does not reset.
Ctrl + Page Up, Ctrl + Page Down back and forth to cycle through the views.