How can I get the seat cover fastener (screw) and it holder out of the body of the toilet? I tried to replace the seat cover and one of the screws is free spinning and will not unscrew.

Underneath below seat hing you will find a nut usually plastic. Tighten it if screw spins on the hinge should be a cover located on top of the screw, pop it up and use a coin to hold it.

You will have to remove the pan to access seat fitment as sounds like a back to wall lol.
Alternatively cut through bolts holding on seat with a hacksaw blade and go to plumb center and buy a new seat with drop through fasteners

Is the nut thats on the under side fastened all the way and If you've done that and the screw keeps getting loose then the threads inside the nut or on the screw may be worn away. If thats the case, you may have to by some new screws and I'm not sure if they sell those separately you would usually have to buy a new toilet seat to get new screws, but try home depot or walmart.

Cut it out David with a flat bladed hack saw with as many teeth as possible. Give it a shot, pays to buy the best HUH????

I have a Toto Dorian 1.6 Gpf where the right side of the cover separated from the seat frame. I fixed it by removing the seat from the toilet base and driving the stainless steel shaft back into the cover hibge holes.

To remove the toilet seat, use a large phillips head screw drive and unscrew the two long screws that hole the seat to the base.

Then you will see the two steel rods about 1/4 inch in diameter that have worked there way out of the seat hinge. Use a hammer and a screw driver to drive these two hinge pins back out into the toilet seat cover hinge holes.

Replace the toilet seat and screw in the two seat screws being careful to not over tighten them. The seat should now work correctly.

Here's what I did. Unscrew them as much as possible. Then I used a bolt cutter and hacksaw to cut away as much of the plastic seat holders as possible. I could then remove most of the seat, and get better access to the screws. I then raised the loose screws enough to cut them with a bolt cutter. Soft screws cut easily. The screw heads are now out. Now, tap down on the screw/anchor and it falls into the bowl. It will stay there. The remaining problem is that you need anchors to secure the new toilet seat. Kohler wants $50. I have a usable but loose seat. Never again-Kohler.
I strongly recommend using a boltcutter. A hacksaw will tear up the bowl.

On top if you look closely you will se that where the hinge is you can lift up a plastic cap and see the top of the screw. From there you can remove screw. It should be a flat head screw.

Good Luck

I have the same low boy where the bolts are inside the hollow body of the toilet. I called Kohler customer service and was told to use brute force to yank the toilet seat out. My husband suggested using a saw to cut the bolt but he hasn't done it yet. He wants to replace all our Kohler low boys which constantly leak becos of poor design of handle and flapper. The handle pulls the flapper slightly to the side when you flush. And the flapper lip being a tiny bit too small, if it doesn't sit just right, the toilet leaks. We've replaced one already with a Toto and love it. Too bad that Kohler isn't trying to fix the problem as I see many many online posts with the same problem and recommendation to replace the Kohler with Toto or somethng else.

Use a flat head screwdriver to pry open the plastic pieces that cover the screws. Using the same flat head screw driver, unscrew the large plastic screws holding the old seat in place. There are usually plastic nuts on the underside that you can hold on to while removing the screws. Remove the old seat. Clean the area where the screws were and dry thoroughly. If the new seat has an adhesive pad, remove the covering from the adhesive and put the seat in place. Thread the new screws through the holes and attach with the new nuts. If there aren't new nuts and screws, you can use the old ones, provided they weren't damaged during removal. Snap the caps covering the screws on the new seat in place. Be careful not to over tighten the screws! Since they're plastic, they can be easily damaged by a screwdriver!

I can't unscrew the toilet paper holder from the wall to move it to a different place. There is only one tiny screw underneath, hard to see and it does not move????? appreciate any advice. Thanks.