we are upgrading IDM from version 12.5 to 12.6. We have an environment limitation that makes us to install a new 12.6 version instead of upgrading 12.5 one. Do you know where are questions and answers stored for each user? It would be good to copy these values so users does not have to fill it again.
You would want to use the IM Management Console to check the IME's AdvancedSettings->Logical Attribute Handlers->ForgottenPasswordHandler to see how it is configured. With a corp!=prov IME the default value would show a physical attribute name of %PASSWORD_HINT% being used to store the values. You can then check the User Directory definition in the IM Management Console to see what user attribute is mapped to the %PASSWORD_HINT% well-known. Note however that the value is likely encrypted and not in a simple readable form of questions and answers.