Welcome to Android Forums. Sorry for the delay in responding to your question.
As new as it is I would take it back or call AT&Ts IT support. Other than that you could try to do a factory reset.
This will delete all user data from the phone.
If you decide to do the factory reset, then you will need to download AppTyrant from the PlayStore. Once you open it up it will auto save all apps to the sd card in their .apk form. If you have an internal sd then move all data that you can to external sd card. Then transfer this data to the computer (just in case).
Once the factory reset has been accomplished open up the PlayStore app and sign in to your Google account. This will give you all your contacts back.
Go to the external sd card (transfer data back to the internal if you have an Internal sd ). Go to the AppTyrant folder (might read Root Uninstaller) and copy/paste all .apks to the root of the sd card (not in any folder, just in the same directory as all the folders. /sdcard). Now just tap on a .apk and choose the install option. When done select "Done". Do this for all .apks (this is way faster than having to locate, download and install all your apps in the PlayStore.
For more info on how to do a factory reset and more phone specific support go here:
Samsung Galaxy S4 - Android Forums
For AT&T All Things Root go here:
(AT&T) Galaxy S4 - All Things Root - Android Forums This is where you will get the needed info to do the factory reset from your phones recovery.
Hope this has helped.
AndyOpie150