I enabled two-step authentication on my Firefox Account by clicking on "Add". Everything went OK. (It was the first time I enabled it. I've been negligent.) The "name" (email) on the token generated by my 2FA App was the primary email of my Firefox Account. Then I clicked on "Change", and followed through the same steps as when 2FA was "Added". Now, the "name" on the generated token was neither the primary or the secondary email of my Firefox Account ! The name on the token was the email I used as the primary email of my Firefox account back in 2020 ! Despite the wrong name (email), the 2FA code worked fine for signing in. How and why does this happen? What is the intended purpose of the "Change" option? I fixed the name on the token by Disabling then Adding 2FA again. A Curiosity?: When I try to sign into Firefox account, 2 emails are offered by Firefox - the current primary email for the account, and the previous primary email for the account. The second email IS in Logins, but not for accounts.firefox.com. The 2nd email is rejected if it is tried to be used. Where is Firefox getting the previous account email from?