Fixing any toilet seat is an easy process, provided you have a screwdriver and an adjustable wrench. Replacing a toilet requires the same tools, along with the new seat.
To tighten a loose seat, pry open the bolt caps by hand or with the screwdriver. Next, hold the nut underneath the seat with the adjustable wrench. Tighten the screw with the screwdriver. To minimize the risk of cracking the porcelain, do not overtighten. Finally, close the bolt caps.
To replace a toilet seat, open the bolt caps, loosen both screws and dispose of the old seat. Next, align the new seat with the holes in the toilet. Fit the screws and nuts appropriately and tighten with the screwdriver and wrench.