The toilet see is not tight. How can I tighten the seat? I have an elongated seat with the soft closing lid.

https://www.choicereplacementtoiletseatshop.co.uk/c/spare-parts/toilet-seat-hinges

some of these have bolts under seat...you turn seat to left or right by grabbing while in closed position...this will release the seat from the holding bolts...then tighten the bolts....then reset the seat on bolts then lock down by doing the opposite as you took off...

The cams are worn out inside of seat or it may be to lose you have to tighten up the seat if there is any adjustments if not it is worn out replace toilet seat.

You will need to remove the toilet and access the bolts from inside the enclosure. It is a dirty job.... good luck!

get a new one under warranty they should work first time

Either live with it or replace it. The hinge is not serviceable and the soft close action does not last forever. They rarely last more than five years, maximum.

You need to replace or clean the 1150464 HINGE KIT http://www.kohlerserviceparts.kohler.com/AccessoriesInformation.aspx?ServicePartID=5563b058e2e042868c7a19398797ecd6

Usually there are plastic caps that snap down over the bolt head.
Shut toilet lid and get down close with a flashlight.

Seat attaches in two places.
Reach underneath and you can feel two bolts with nuts.
You don't need to see them, just feel with your hand.

The bolt head is covered with a plastic cover.
The cover is added for aesthetic purpose only.
Use small screwdriver or fingernail file or nail or scissors to pry up the cover and reveal bolt head.

Use bigger screwdriver to tighten bolts.
You may have to keep one hand on underside to hold nut while turning bolt clockwise.
Another trick is use hand to push bolt all the way up, and then finger tighten bolt most of the way, and use screwdriver for last few turns.

Tighten bolts good and tight, but don't overdo it.
Bolts will come loose again and you can tighten more later.

seat hinges were tightened out of alignment. Loosen platic nuts and tighten snugly, rotate hinges to bein line and tighten

Call kohler they do have replacement cylinders