Hi Marco, the Sync data should start appearing over time as Sync runs in the background, but if that isn't working, you can manually transfer some files. Those files would be in your profile folder -- note that you might have more than one profile folder; you want to copy from the most recently active folder to get your latest data.

More info:

• Recover important data from an old profile
• Profiles - Where Firefox stores your bookmarks, passwords and other user data

If you set up your computers with the same Windows user name, then you also could take a look at the "folder transplant" option:

https://support.mozilla.org/questions/1321847

(When reviewing that thread, substitute the actual location of your source folder, whether in a backup or cloud folder or external storage, etc.)

Thanks jscher, so should the Sync work alone to do this job? If sync is done for this I'd like to open an issue since it is not working. Otherwise if the aim of sync is another one (cannot imagine which one) than I will try one of your option. I hope they are safe and easy to follow :D Sadly I'm not sure the target pc have the same username, the old one is a company pc and the username is my company id, I'm not that much happy of carrying my company id everywhere.

If there is any other easy way let me know.

You can copy certain files with Firefox closed to the current profile folder to transfer or recover personal data. Note that best is to avoid copying a full profile folder.

You can use the button on the "Help -> More Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page (Root directory).

• Help -> More Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

• bookmarks and history: places.sqlite
• favicons: favicons.sqlite
• bookmark backups: compressed .jsonlz4 JSON backups in the bookmarkbackups folder
• cookies.sqlite for the Cookies
• formhistory.sqlite for saved autocomplete Form Data
• logins.json (encrypted logins;32+) and key4.db (decryption key;58+) for Passwords saved in the Password Manager
  key3.db support ended in 73+
• cert9.db (58+) for (intermediate) certificates stored in the Certificate Manager
• persdict.dat for words added to the spell checker dictionary
• permissions.sqlite for Permissions and possibly content-prefs.sqlite for other website specific data (Site Preferences)
• sessionstore.jsonlz4 for open tabs and pinned tabs (see also the sessionstore-backups folder)