Hello there,

Firefox automatically saves browser settings and bookmark backups. Restore a backup from prior to when you set up Sync.

https://support.mozilla.org/en-US/kb/restore-bookmarks-from-backup-or-move-them#w_restoring-from-backups

Hope this helps!

Which Firefox version did you use before?

Firefox 29 and later versions use a new Sync version that use a Firefox account and only require to enter the name and password and you no longer need to enter a Sync (recovery) key (the Sync key is automatically generated from the password of the Firefox account).

Note that if you change the password of the Sync account or request a new password because you do not remember the password that this will remove (reset) all data stored on the Sync server.

Thanks, unfortunately it doesn't work (I guess that's different problem). My question was how to go back to all my settings from before Syncing. Now I have even different coulours of the browser. It's not only about bookmarks.

These can't get your data back, but will help in the future.

These add-ons can be a great help by backing up and restoring Firefox

FEBE (Firefox Environment Backup Extension) {web link} FEBE allows you to quickly and easily backup your Firefox extensions, history, passwords, and more. In fact, it goes beyond just backing up -- It will actually rebuild your saved files individually into installable .xpi files. It will also make backup of files that you choose.

OPIE {web link} Import/Export extension preferences