Stop my Apple devices and PC desktop syncing Mozilla bookmarks I have a MacBook Air and iPhone 7. I have a Dell desktop at work, and for some reason my Firefox bookmarks from my work PC are showing up on my Apple devices and I would like to remove them. At work I use Firefox, IE, and Chrome. On my Apple devices I use Safari and Chrome. I assume iCloud might be the problem here. I am wondering if (since I use it on all three devices, it is somehow syncing them. The shortcuts from my Firefox toolbar show up in my favorites on my Apple devices, and the bookmarks from my Firefox bookmark menu show up in my Safari bookmarks folder.
I assume you're talking about your Firefox bookmarks. If your bookmarks from work are showing up on your personal devices, then it's most likely because you're signed into your Firefox account on all your devices. 

If you don't want to sync these devices with the same Firefox account, you should either create a different Firefox account for your personal devices, or not use a Firefox account at all for your personal devices.

For example:


on your MacBook Air launch Firefox and go to Firefox > Preferences > Firefox Account to view your account settings.
on your iPhone launch Firefox and go to Settings. At the very top you'll see your Firefox Account details.