You can edit your app’s icon image by logging into your App Manager, selecting your app, then clicking the Applicationtab.
Next click the Application icon button.
You can also edit your upload icon image (and color) from this screen. Simply click the “Upload icon” button.
Be certain of the images you want to use for your app Icon because you cannot reset to the previous settings.
IMPORTANT NOTE:Your app will have to be republished to the respective App Store in order for the change to be reflected in your live app.