A loose toilet seat is uncomfortable to sit on. It will wobble, slide and shift under you, making you feel as if you are about to slide off the toilet. Most toilet seats are held on the toilet by two plastic bolts run through holes at the rear of the toilet bowl and are secured with plastic nuts. Over time, these bolts work loose, allowing the seat to slip from side to side. Tightening these bolts normally will stop the slipping.

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Pry up the seat-bolt head covers on the toilet seat's hinges, located at the rear of the seat, using your fingers or the small screwdriver. This exposes the slotted heads of the seat bolts. On most toilet seats, there is a little notch on the seat-bolt head covers for a screwdriver to pry up the covers.

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Insert the large screwdriver in the slot of the plastic screw head and turn it clockwise to tighten the seat bolt. Most plastic seat bolts have a nut with a wing that keeps the nut from turning as the bolt is tightened.

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Hold the nut of the toilet seat bolt using pliers if the bolt keeps turning without tightening. Maneuver the pliers up under the lip at the back of the bowl until you can feel the nut of the toilet seat bolt. Grip the nut with the pliers to stop it from turning while you turn the slotted bolt head with the screwdriver to tighten the toilet seat.

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Snap the seat-bolt head covers back in place once you've tightened the bolts securely.