Firefox 33: i block www.google.rs from making cookies, but that setting is gone next time i start firefox. The page permission settings also vanish (not saved).

I delete ALL cookies and under Privacy settings i block www.google.rs from creating any cookies. But that setting is simply gone (not saved?) when i start firefox next time, and www.google.rs is again allowed to make cookies. I try setting Page permissions under Page Info, making sure i block everything so that www.google.rs is not allowed to do anything. Next time i start firefox, the Page permission settings i chose for www.google.rs are reset to default, and www.google.rs is again allowed to make cookies. Please look into this issue as soon as possible. Thank you for helping.