I have Android 5.1.1 Oppo R7kf, How do I set my SD Card as Default storage when there's no available options to set it?

[sidrexponsica]

I have Android 5.1.1 Oppo R7kf, How do I set my SD Card as Default storage when there's no available options to set it?

 

[webworkings]

You can't. You have to be running at least Android 6.0 (a.k.a. "Marshmallow") for that option to be available.