Unless that phone has been rooted, it shouldn't allow for running apps off the SD card. At least not most apps. You would need to be running at least "Marshmallow" to get that to work. Your device should only run up to "Lollipop". Now if you can upgrade to "Marshmallow", the instructions for setting up the SD card correctly are included below.
If you have rooted the phone, that I can't help with. You would need to post in the "Rooting, Jailbreaking & Unlocking" Forum.
http
/www.tomsguide.com/forum/forum-117.html
How to turn external SD card into internal storage on "Marshmallow".
NOTE: Please be sure you start with a blank SD card. It needs to be blank because when the card is converted to "Internal" storage, it will be formatted (wiped) and encoded (making the cards data only readable by that device).
1. Go to device “Settings”, then select “Storage”.
2. Select your "SD Card", then tap the “three-dot menu“ (top-right), now select “Settings” from in there.
3. Now select “Format as internal”, and then “Erase & Format”.
4. Your SD Card will now be formatted as internal storage.
5. Reboot your phone.
NOTE: If you don't reboot the phone, many things may not work correctly, so make sure you do.