Why doesn't FireFox ever remember what i set it oto do?

see ive had mozilla for a while but now that i have put on yahoo toolbar when i open mozilla a dialog box shows saying if i want to change my settings and i put no and to dont show this message again...but when i reopen it, it shows up again and it is annoying....also when i put to keep me signed in to yahoo mail it never does....so how do i make it remember my things and not come up again??pls hlp