I also just learned that Android Opera does not sync passwords anyway. At least that's mentioned in http://www.opera.com/help/account#sync.

For extra fun, I've tried multiple times to reset synchronization. The account seems to be cleared, but it's repopulated even though I don't tell Opera to log in. When I do login, I invariably get asked my password. So I can't switch back to syncing without a passphrase.

Guess I'm creating a new account—if that fails I might have to sadly give up on Opera.

Hi, I've created an Opera account to sync across OS X and two Android devices. On OS X, I chose to encrypt all synchronized data with a master passphrase. But I can't tell the passphrase to Opera on Android. That's not discussed by instructions on http://www.opera.com/help/account, and I found no way by playing around in the interface or searching these forums.

For now, I'm resetting synchronization and disabling it for passwords—encrypting passwords only by a password that Opera has is not robust enough—even if I trust Opera's honesty, that's no guarantee if Opera's DB is hacked.