Reviving this thread for those struggling. I had the creaking driver's seat and found a solution.

Remove the drivers seat from the car first. Lay it on it's back. You'll find a total of four large star bit bolts holding the seat tub to the base/bracket assembly. My creaking was coming from the joint between the seat bracket and the seat tub at the location closest to the seat belt receiver.

I removed the seat base by removing all of the large star bit bolts. At the location closest to the seat belt receiver, the star bit bolt has a large shoulder design that fits through the seat tub and then threads into the seat bracket. I added a layer of felt (with a hole in the middle for the threaded end of the bolt to go through) so it gets sandwiched between the seat tub and the seat bracket.

The creak is now gone.

 

Update: Creak came back and I found that the felt tape had squeezed out of the joint. Be really careful on re-install that you don't shuffle the tape out of place. Or, an even better idea, which I'll do if it happens again, get yourself a super thin teflon washer instead of using tape

 

I have to admit, I wasn't super comfy with the idea of a compliant washer where seat mounting was concerned.

 

I'm talking a 0.01" washer. If you're concerned about that idk what to tell ya 😂

 

Well, I spent several hours figuring this out today. It is as NEOEvora said above. The large bolts that need a T-40 socket are the culprit. Remove the seat (4 plugs to undo, airbag one is odd and challenging), lay it on a blanket on its back. Remove the bolts (pic below) and pry apart where the seat runs against the metal frame. I inserted a double layer of felt, cut from a reusable Lowe's bag, and then tightened it back up. You can sit in it while on the floor to test, but it fixed mine. Hated that creaking sound! Was mostly the rear bolts, but can do fronts as well.

 

Check seat mounts then the sliders.