Paint the screws with Maybelline Crystal Clear Nail Polish. It will seal the screws and if needed to unscrew them just apply polish remover! It works like a charm and your toilet seats stay looking nice..
The screws now are all plastic so no problem! I can't remember ever seeing metal ones.
Preventing Rust
Putting Contact Paper Over Wall Tile in a Bathroom?
Decorating a Child's Car Seat
Use an Egg Carton for Painting Bolts and Screws
Removing Liquid Toilet Bowl Cleaner Stains from a Toilet Seat?
Finding Help to Make a Bathroom Conversion for the Elderly?
Organizing Nails, Screws, Nuts and Bolts