Changing the eyes on a inset eye doll:

Heat until the head is flexible, use a screwdriver, chopstick or hemostats to push the eyes out at the sides.

To replace the eyes: find which area of the socket has the most outer plastic, reheat the eye sockets and place it in there (sometimes it’s the lid, sometimes it’s the cheek side) then use your chopstick to pull up the plastic from the other side of the eyesocket.