Try clicking on show advanced settings or go to private mode, you should see the option once there.

I've been using Opera for years, however... Since the last week it hasn't let me modify settings.
Everytime I click on "Preferences", Opera freezes and whatsoever doesn't seem to answer any command.
I've tried updating the browser and still nothing. I've tried using Opera, Opera Beta, Opera Dev and even Opera Neon.
Same problem with all of them. I refuse to use any other browser though, Opera's the only one comfortable for my eyes.

What can I do?