Can't change App Store preview images on App Store Connect

I have an app that got approved yesterday and is now available on the App Store. When I look at the app in App Store I noticed there's a misspelling on one of the preview images (screen shots) of the app. The misspelling is not in the app itself, but on a promotional subtitle on one of the preview image. However, when I go into App Store Connect everything on app page is greyed out, so I can't change screen shots, description etc. It says "Ready for Distribution" in the top left corner even though the app is already released. I thought you were able to change these things without uploading a new app version from Xcode, so why can't I change any information?