Per-Viewport filtering allows for an easy and efficient way of filtering the visibility of geometry, lights, cameras, and other objects in a scene. Each viewport's filter settings can be set independently from one another, giving you the flexibility to display what you need in a given viewport at any time during your workflow.
Per-Viewport filtering is set to off by default. Enable it by clicking the icon shown below. Access filter settings by right-clicking the icon. You can also use Shift+K to toggle on and off the viewport filter.


will toggle on Per-Viewport filtering. Default=off.
will copy the Per-Viewport filtering settings from the active viewport.
after copying Per-Viewport filtering settings will paste them into the active viewport. You can switch the active viewport while keeping the Per-Viewport filtering settings dialog box open.