You need to login from your old account:
[content.overture.com...]
after you login you will see that you can do 2 things only:
1.Your Account Upgrade Is Complete. Log In Here.
2.Pre-Upgrade Reports And Listings Are Still Available Here.
you need to choose number 2

I confirmed with the YSM support team that upon 'Upgrade' to Panama, it is as if you are starting a brand new account. So your reporting in the new interface will begin the day your account successfully upgraded. If you work in heavy statistics like I do, this is a headache. In order to gather month to date stats and historical stats, you have to use *both* interfaces and manually add the data together.

Hi there,

I thought I’d jump in here to confirm that once you are in the platform you can still access reports in the old platform and explain why reporting in the old platform has to remain separate from the new platform:

Reporting– As a part of the upgrade of accounts from our old platform to the new platform, the search listings in the old platform are transformed into ad groups and ads in the new platform. Because the old platform’s reporting system was based on that listing structure and the new platform’s reporting system is based on the ad group and ad model, the data aren’t comparable. It wouldn’t even be like comparing apples and oranges; it’d be more like apples and Volkswagons. For that reason, we’re allowing advertisers access to their reports in the legacy platform for an extended period of time.

Access to old system – Once an advertiser has upgraded to the new platform, the account is disabled in the old platform. Any changes that one could have made in the old platform would no longer be effective, so access to that functionality is no longer useful. That said, we will continue to provide access to reports via the legacy platform.

YahooSarah