This add-on is good at deleting ordinary cookies, but, unlike Self-Destructing Cookies, it doesn't offer the option of hiding the window and turning off the noise when cookies are being deleted. It's especially irksome when I'm listening to music while browsing. I would very much appreciate it if you could add this option.

Edit 1
Thanks for your reply. Yes, I'm referring to the noise that comes with the notifications. I downloaded the add-on yesterday, and the preferences page showed the "welcome" text, but not the settings. Now it does. I haven't checked "Show Notification After Cookie CleanUp," but that hasn't had any effect. I've clicked "SAVE," but there's no indication that anything has been saved.
One last thing: After each setting there's a question mark, but when I click on a question mark nothing happens. I had hoped that clicking would show a short explanation of what the setting does. It would be helpful if it did.

Edit 2
I deleted Firefox and re-added it without the old files, and now I have access to the settings. Everything seems to work as it should. Thanks for your help.