With Firefox Sync, the changes made on one device should be reflected in all other devices. Where I find that some people run into issues with when they first start using Firefox Sync is getting everything merged into the account without duplicate data.

If you press the Sync Now button in the Firefox menu, that sends any missing data from your device to the Firefox Sync service. Then, when you open a different device, it should compare the data that it has with the data that is on Firefox Sync and pull any missing data onto the device.

However, I have noticed that some people have issues with Firefox detecting the same bookmark on multiple devices that was created before starting to use Firefox Sync as two separate bookmarks and trying to add two copies on the Firefox Sync service.

That said, once you get through the initial first few syncs with your devices, Firefox Sync should work the way that you have described above. Firefox Sync is always a bi-directional sync (both uploading and downloading), but it should only be mirroring changes.

Thanks, Wesley. I think what I'll do is uninstall Firefox on two devices, and on the third I'll delete duplicates and clean up the material to be synced. Then I'll log in and sync. Hopefully when I reinstall Firefox on the other two devices and sync, there will be no more duplicates.