Hello,
You just need to clean your phone. Download Clean Master and run it!
You can't set your SD to be default storage (if your phone is not rooted). Just transfer your data from your internal storage to SD card... (read this -> http
/www.tomsguide.com/faq/id-2908201/move-apps-card-android.html). Is it okay now?
Regards,
GeRgY