Unscrewing: hold the plate/frame down, remove the screws, then lift the plate/frame up slowly until the spring pressure is released. Single screw with spring: keep screwdriver in positive contact with the screw with a light downward pressure while turning the screw until the screw is disengaged from the threaded part it is screwed into then slowly remove the pressure until the spring tension is released.
Installing: put the springs in place, sit the plate/frame on the springs ensuring they sit into their sockets/pads on the plate/frame then press the plate/frame down down into position and hold, start a screw in one corner by at least 3 turns then start the screw diagonally from the first then the last two screws. Tighten the screws in an X pattern, snug at first for all screws then final torque. Single screw: put the spring onto the screw, position the screw onto the part, press down with a screwdriver firmly in place in the screw head and install as normal keeping downward pressure on the screw until at least 3 turns have been reached.
Apply a drop of clear nail polish to the tip of the screw before installing it to lock it in place when tightened or apply a drop to the screw head base just before reaching contact with the mounting surface to hold it in place/prevent it from loosening from normal use vibrations.