Comment #4 on issue 233 by
jon...@google.com: Got new phone now
This only moves the google account codes. Other (3rd party) credentials
are left on the old device.
Your options:
1. Apparently rooted phones can backup / restore these.
2. Also, if you still have the code from the 3rd party site, you might be
able to reuse on new device.
3. But, for most of us, the only the only option seems to be:
• Disable 2fa on the account in question (eg dropbox).
• Delete account from Authenticator on the old device.
• Setup new 2fa for this account again on new device.
Will report back if I find a better way.