How to Replace a Toilet Seat
Push the anchor bolts of the new seat through the holes and hand tighten the nuts.
Align the bolt holes of the new seat with the holes of the toilet base. Push the anchor bolts through the holes, and then screw on the nuts from the underside of the bolts until they’re hand-tight. Center the seat and then tighten the nuts.
Once the seat is centered, use the adjustable wrench to tighten the nuts. Don’t over tighten the nuts — just beyond snug is good enough.