Firefox 29.0 (currently beta) and later use the new Sync version that use a Mozilla account and only use the name and password and no longer use a separate Sync (recovery) key (the sync key is automatically derived from the password).
As this version is completely different from the version previously you need to use Firefox 29.0 and later on all connected devices, so you need to install Firefox 29.0 on all other devices as well.

You can enter the name and password of the Mozilla account on other devices that have a Firefox 29.0 or later version to add extra devices.

• https://support.mozilla.org/kb/how-to-update-to-the-new-firefox-sync
• https://wiki.mozilla.org/Identity/Firefox-Accounts

• https://blog.mozilla.org/services/2014/02/07/a-better-firefox-sync/

Sorry, I should have clarified my main issue. My devices are synched, however, when I try to share a tab from my Android Firfox to my desktop my desktop is no longer listed as an option to sync with. History, Passwords, etc are all synched fine, but I cannot send a tab. This is pretty much the whole reason I use sync. I restored my old Firefox on my Android and it now gives me the option to send the tab to desktop, but it never gets there. That is the screenshot with only the desktop option. Then I removed all devices and added them back and now I get my desktop and 2 for my phone to send it to itself - none of which actually recieve a sent tab

Are you using Firefox 29.0 Beta on all those devices?

If not, the Sync features available on devices / PC's using Firefox 28 or earlier are going to function completely (if at all - mine don't with old and new Sync devices on the same Sync account for a couple of months now) with a Sync account that has been run with the new Sync version. The assumption is that users are using a Release version and all devices would be updated to Firefox 29 at the same time, once Firefox 29 is officially released on April 29.

The Beta, Aurora, and Nightly pre-release versions (currently 29.0, 30.0b#, and 31.0a#) are available for anyone to download, install and use, but they are intended for "testers". For those "testers" to get involved in the development process and to provide feedback for helping Firefox release by catching Bugs that might creep into the development process during the 3 stages (known as Channels) of development.

There are 4 Channels in the process - Nightly, Aurora, Beta, and Release. Firefox spends 6 weeks in each stage, until it is "yesterdays" version.

What a nightmare this f-g Firefox Sync!!! I spent hours trying to do such a simple thing as to first use my home computer to sign in in order to be able to use my settings on my work computer at work.

The problem is that the steps I see on "How To Sync Your Browser Data with Firefox Sync" at http://www.howtogeek.com/105389/how-to-sync-your-browser-data-with-firefox-sync/ , I do not see them on my Firefox 29.0.1 version (now 30.0!) when I tried FF Sync. In particular, I do not have a link called "pair a device" on my home computer and neither at work when I tried to pair my home computer settings with my work computer.

More, to expect user to stay connected for this sync feature INDEFINITIVELY is not only unrealistic, it is stupid. As soon as I signed in, I expected Firefox to take just a few minutes to download from my home computer the various options I chose to use for Sync (addons, etc.) and that is it, no more needs to stay connected ad infinitum for this F-G Firefox sync feature when I stay connected at least 30 min!!

To say that I am very upset with Firefox is an understatement. When I saw several articles showing a "pair a device" link and when I could not see such a link when I set up Firefox Sync, it is extremely upsetting, to put it mildly!!

That are instruction and screenshots for the previous Firefox version.

See:

• https://support.mozilla.org/kb/how-to-update-to-the-new-firefox-sync
• https://wiki.mozilla.org/Identity/Firefox-Accounts

You can still disconnect from the new Sync via the Options > Sync window or by clicking the Firefox account name (email) address in the "3-bar" Firefox menu button drop-down list.

Your suggestion did not resolve.

Please anyone know how to make work this damned sync? No option to pair with other device. 30.0 the version.

As long as all your devices use Firefox 29 or later (i.e. the new Firefox 30) AND have been upgraded to the new Sync then the Old Sync is no longer needed or used.

_{It will be possible to continue using the old Sync, for instance if one of the devices is a corporate desktop using ESR, but you must then not upgrade any of the devices to use new Sync or they will not be able to continue to use Old Sync.}

I never used. I would like to use it.

I am just starting!!! I do not have any chance to define a target device because I HAVE NO OPTION to add devices with which I could sync !!! 

It simply DO NOT WORK as described by You and Firefox Helps!