can't make sd as a default storage for photos

[macoy enriquez]

Hi guys,
Need some help here in my device. I have samsung galaxy s4 mini and i set my storage for photos in sd as a default., for a few weeks it works just fine., but suddenly it changes its default storage to my device., when i change it back to sd and take a photo again it will put it back again to my device. What should i do? Thanks.