Just a quick step by step guide for those that don’t know how to move your apps to the SD card.
*no root access needed.
1. At the home screen, click the menu button. Then click settings.
2. Now scroll down and click on Application Manager.
3. Find the app you want to move and click on “Move to SD card”
Or if the app is already on the SD card you can move it back to the phone. If the app doesn’t support being moved to the SD card then it will be greyed out.
Now if your Galaxy S4 is rooted, there is an awesome app called /System/App Mover. You can get it from the Play Store Here. It can take apps from your system and move then to the SD card or take regular apps and add then to the system partition. Its very useful.