Posted this here as I'm not sure what category this falls into, as we don't have a "clueless" one

Due to changing our holiday I am going to have to cancel nearly all of our ADRs, but I can't seem to find where to do it on the WDW site. I believe it may be something to do with my Mac, browsers, cookies, and other techno-type things I don't fully understand as I do know some other people are having no problem cancelling on the Disney Dining site. But maybe I am just being totally dim and not even seeing the right page! I have cancelled things before on there last year. I can do it over the phone, I know, but I'd prefer not to if possible. Any ideas please?