Showing how to reattach the earpd for sennheiser momentum headphones. As you can see it can be frustrating and may take several attempts. You have to work your way around slowly, each time retain a firm grip on the completed areas so they don't slip back out.
It took 3 attempts to finally get it right.
I recommend NOT removing these ear pads unless absolutely necessary (like maybe for cleaning, or repairs, or you're sadistic and like torturing yourself lol)