samsung android 6 grant sd card issue

Hello everyone. I upgraded my Galaxy a3 2016 to android 6.0.1 marshmallow. but I can't grant sd card to make full access like android 5.1.1 .... in android 6 , shows a notification that says "explore sd card" and I can't delete my files in third party apps like quick pic and I can't use sd card on titanium backup and I can't set custom location in ADM. I tried to find "platform.xml" and set it manually but sd card lines missing. why?!!! many people have my issue. please help me to grant my sd card on my galaxy a3 2016 in android marshmallow. thank you.