I don't think the QR code is mandatory for desktop systems.

On whichever Firefox isn't connected to the account, try signing in from the menu (main menu button > Sign in to Firefox). I believe there will be an email verification message generated to your primary email account for the initial setup, and that may involve either a code or a long link.

There is no need to use a QR code. All you need to do is to connect to the same Firefox account.

• https://support.mozilla.org/en-US/kb/how-do-i-set-sync-my-computer
• https://support.mozilla.org/en-US/kb/access-mozilla-services-firefox-account

Hey cor-el, hey jscher2000,

thanks a lot for answering my question. Apparently it just took some time for Firefox to synchronize with synch now after connect the different apps to the same account.