If you have your own developer account this is the only way that you can change your iOS screenshots that show in the iTunes Store!
Here's how to update the screenshots if you have your own iOS Developer Account?1. We have to resubmit the app and for any submissions that are purely cosmetic like this one there is a $99 resubmission fee. (If there is a bug that we can identify that requires a resubmission in your app that we have not already fixed we will incur the cost and resubmit the app)2. Once it's in "Waiting for Review" status, go to the app and click "View Details" under the "New Version"3. Click "Edit" next to "Metadata and Uploads" and i think you got it from there! :)