* With Sync there is no user control beyond selecting the data types to Sync per desktop / laptop device. All data is made the same on each device, ''within certain parameters as to desktop / mobile differences''. * "Synchronization" is done on the Sync server, there is no directional control by the user. The server controls the data to and from each connected device. Documentation is poor to non-existent for Sync. The requests that I have made to have a Sync developer author a few basic Knowledge Base articles in the contributors / moderators / administrators side fora have been met coolly; "write something up and we'll review it, edit it, etc". I have been down that road too often, to write an article and let it be kicked about; then the net result completely differs from the intended point that I was trying to make. Then the few times a Sync developer was gracious enough to answer a specific question here that I have PM'd him about, I discover that my perception of Sync is off enough to make me look stupid with the answer that I had made previously. Not my job to create documentation for Mozilla, especially since I haven't needed Sync for my own use since Firefox 4.0 came out in March 2011. ''Merely played with Sync on the same PC between to separate Profiles for Firefox. The Profile level is where user data is stored and used from. Similar to Windows Logon User Accounts, but at a different file structure level, which allows Firefox to have multiple Profiles for the same LUA in Windows.'' * As far as Bookmarks go, the '''Firefox for Android''' & '''''for iOS''''' are handled slightly differently that the Firefox Desktop / Laptop builds, with the Sync server. Corruption of bookmarks doe happen and it is hard to fix correctly; a specific set of tasks to do, in the correct order, and with no shortcuts OR the problem won't be completely fixed. Sorry, can't help you with that. * Whatever, there is a real easy way of clearing ALL your data from the Sync server, merely change your Firefox Account password! That password is used to create the concretion algorithm for Sync data that resides on the Sync server ''(and while off on each device and "in transit" to / from the Sync server)'' as a "BLOB" that can't be read ''[even by Mozilla, who doesn't have the "key"]''. Different password just won't work, so the data is cleared to allow the user to keep using that same Sync / Firefox Account.'' * Deleting '''''one''''' bookmark from Firefox will be almost immediately sent to the Sync server. But if the user deletes multiple bookmarks in a row, those deletions will be delayed ''(my experience / observations)'', and then when Firefox thinks you're done, that data is sent in a stream to the Sync server. Too may sequences like that, too quickly, and the Sync server may "miss something" and the user ends up with corruption! Desktop Firefox does have a '''Verify Integrity''' feature for the Places Database, in Help > Troubleshooting Information, near the bottom of that long '''about:support''' internal page @ '''Places Database'''. With "mobile device" ''Firefox for ...'' versions the Sync server handles that automatically ''(supposedly)''. And the server also handles a lot more with regards to bookmarks, from what I have read. As far as re-organizing a "mess", especially from multiple other devices goes; '''Sync will make matters worse the faster you trying to organize that mess'''. Disconnect from the Sync server '''before''' doing that type of intense job, and slower is necessary if connected to Sync while doing even minor changes. And don't proceed to another device until the current one is reconnected to the Sync server for a few restarts of Firefox.