I’m really sorry to hear about this.. Firefox and Apple’s iCloud web apps unfortunately not always work together perfectly, since Apple’s online apps are for Safari and sometimes Chrome. That said, I completely understand how annoying it must be if something as basic as copy-and-paste doesn’t work reliably. If you’d like, you could file feedback with both Mozilla (via Bugzilla ) and Apple (through their support page), so that both sides are aware. Firefox developers do review reports like this to improve compatibility where possible. Of course, you should use the browser that best meets your needs.. but if you ever want to give Firefox another try, the community here will be happy to help!