how can i save highest played level?,how can i save number of highest played level?

hey guys.I m making game and want to save highest played level or scene. Need to use it in "levelselector". I was trying to use playerprefs but , i did folow brackeys tutorial for level lock unlock. It works but not as i wanted bcs when i did leave game or go to the other scenes it has reset but i don't want it. So i need save something like number of highest played scene save it somewhere adn use it too in level selector. don't know what to use it