I have a 2005 Civic LX in which the driver sides seat moves around. I can't tell if the movement is coming from the bottom of the seat or the back support. Where are the bolts that I need to tighten for both the bottom and the top supports? Thanks!

 

There are 4 bolts that hold the seat assembly to the floor (they are underneath plastic covers). If those are already tight, remove them to take the seat out of the car so you can turn it upside down and reach the internal bolts. Often this is damage to the frame of the seat due to a crash, in that case the best thing to do is replace the whole seat from the floor up.

 

It's the bushings, common problem with 7th gen Civics. There's a TSB but no recall.

DIY: Driver's Seat Rock (oddmut) - Honda-Tech