Sliding padio door leaking at the bottom , water leaking on flooor beneath carpet into wood floor then into ceiling of living room below it causing damage to ceiling .

You need to properly seal the outside of the bottom of the patio door from the outside. Use a good quality silicone sealer at the proper temperature outside and let it properly cure before it rains. I would seal the entire door frame on the outside as well just in case the leak is coming from the top or side of the door.

Remove door panels from frame. Remove bottom track. That may or may not require removing the side jams. Clean surface under bottom track and put a bed of either Liquid Nails or silicone. Reinstall bottom track.

Just sealing the outside or the track edge may work for a while but chances are the seal will break or crack in the future and the problem will come back.

I see this too when there is not proper flashing at the outside, under the door. Do the suggestions above, and in the summer - check to see if you have flashing.