Editing screenshots in iTunes Connect after iOS app was approved

Apple support now got back with the (somehow not too satisfactory) answer:

If your app is currently for sale on the App Store, you will need to submit an update in order to change your app screenshots.

If you have any further questions regarding this, please let us know.

As of today, it appears you can't edit screenshots after you submit a new version. I tried everything but couldn't delete the draft screenshots until I finally removed my app from submission.

I usually use the time after submission to edit and improve the screenshots, but now have to be doing it before submission. This is a horrible change. Here is the email from support.

Being unable to now edit screenshots while an app is in "Waiting for Review" status, is expected behavior.

Developer-facing documentation currently lists "Waiting for Review" as a state where locked metadata can be edited. Screenshots should be the only locked metadata that cannot be edited while an app is in the "Waiting for Review" status.

We are currently updating the developer resources and documentation to clarify

The current standing on this has changed to:

Beginning January 9 [2013], app screenshots will be locked in iTunes Connect once your app has been approved. New screenshots may be uploaded when you submit a binary for an update to an existing app or a new app.

I was able to change my screenshots after my app was ready for sale, just click on "View Details" in iTunes Connect, delete the old screenshots and replace them, then "Done". The change is not instant so wait a bit. Then you will see your new screenshots on AppStore ;)