Aren't we supposed to edit PlayerPrefs's stored file manually on OS X?

Hi, During the development, I manually altered the plist that stored PlayerPrefs data several times but today, aside from "when it rains, it pours", when I edit the plist and run the game via editor, it restores the values! Am I doing something wrong? Location of file I'm altering is Users/MyUsername/Library/Prefrences/Unity.mycompanyname.mygamename.plist Thanks