I got an S7 edge a few weeks back and was excited about the external SD CARD support. Unfortunately it's still not integrated very well. You still have to go in and manually set it all up. Apparently Android Marshmallow has support for creating a seamless file system across internal and external storage.

The easy way

This is I guess how they wanted you to manage this stuff

Settings Menu

Storage Menu

Apps list

Here is an app that can't be moved. Anything that came pre installed on the phone appears to be pinned to internal storage.
Example of non movable app

Here the Messenger app can be moved
Example of a movable app

Tap the change button then you'll be presented with this option.
location selection dialog

Confirm you want to move the app
Move Confirmation

Transfer in progress screen
Transfer in progress

Back on the messenger application screen you can see that it's now on external storage
on external storage

Android Ninja way

With ADB apparently there is a way to enable the native android file system spanning in Marshmallow (my non standard term for it) that will be another write up.