Having trouble switching storage to SD card

[RealestArtiste]

Okay, I've already read a bunch of other posts about how to do this, but I'm not having a whole lot of luck. When I go to storage in settings in the spotify app, I can see the sd card that I want it to store to, but it is grayed out. What is the deal? I've included a screenshot of the screen I'm inquiring about. 

   Thanks,

                   Art

[Joe · Accepted solution]

It looks like your cache in internal storage is using 4.1GB but there is only 3.5GB of free space on th SD card. Sensibly, the SD card is greyed out. Delete some stuff from the SD card to free up space.

[Soccerbuddy]

I have almost all the sd card free of space and it shows the 2 options to choose from, but I push the sd card option and it does nothing, the check mark stays on internal space option... why? Please help