Question about the flush handles for toilets. I've replaced 2 of them and now it seems that both have to be held down to flush. If I don't hold them down, they quit flushing. What did I do wrong?

It sounds like the chain connecting the arm to the flapper is too long. A long chain wouldn't pull the flapper high enough, allowing it to be pulled down by the water suction. Relocating the hook so that there's just a little slack in it when the valve is closed and handle released should permit the lever to pull the flapper high enough to float until the water level drops to the bottom of the tank.