There are a lot of threads on this subject, so I have to wonder why you didn't do a search before posting? It would have given you a faster answer as well.
Google search: script swap external internal sd storage samsung xda
I used mattiadj's script on the S5 with good results
Why don`t you use FolderMount https://play.google.com/store/apps/d...e.fmount&hl=nl and here http://forum.xda-developers.com/show....php?t=2192122?