If your toilet seat slides around there is a way to fix it without having to buy a whole new seat. Mine was forever loosening from the grand kids climbing up on it to see their selves in the mirror. Seemed no matter which brand I bought in 3 months I was buying another one. Then I found this article and it told me why and what I could do about it. I did it and it has stayed tight for over 2 years now. Thanks Family handyman.
Toilet Seat Repair: Keep Your Seat Tight