If you are planning to do that because you need more memory for games,,,better try directory bind or folder mount app...
To swap them permanent,,, u need root..and quite knowledge or you may mess the partition of your device... But no problem if you have recovery installed... Just edit the vold.fstab file.. Search how to do it..
thank me if I helped you...Don't say it,hit the button...
Sony Xperia E dual C1604
MY OWN NoZ ROM
STOCK KERNEL WITH CWM.....
HIT THE THANKS IF I HELPED YOU...IT'S FREE ACTUALLY BUT MEANS A LOT TO ME