When your app is submitted to the app stores for approval, there will automatically be screenshots taken of your app to be displayed in the stores. It will take screenshots of the first 4 tabs in your app. The first screenshot displayed with be of your first tab, the second of your second tab, etc. Therefore, make sure that what you have display first in your app when it is submitted is not time-sensitive. For example, if you have current events sliders on your home page, you'll want to put a generic image in the first slider spot so that the out-dated image isn't what appears on your app in the App Stores. The generic image can be removed after your app is approved, but this way your screenshot will always be current.