App Screenshots Can No Longer Be Changed After an App is Approved
Apple has informed developers that they will no longer be able to change app screenshots once their application has been approved.
Beginning January 9, 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. For more information on capturing and using screenshots, read the Xcode User Guide.
This is somewhat of an inconvenience to developers who had the ability to swap out screenshots if they detected a problem or wanted to highlight a specific feature since only five screenshots are allowed.