how to use my sd card as my internal storage ? please help me

[gracethine.01]

Everytime i tried to download some apps my phone always showing free up some space even thou i have sd card

 

[Saga Lout]

That option only works in Android 6 or later. It only works with some Apps because there are those which have to live in the system folders so it isn't always a wise move to dedicate the SdCard to be used as Internal Storage only.

To find your version number, tap the Apps square then Settings>More>About Device.