Sorry about the delayed response, I have been traveling for the holidays and am seemed to have caught a cold in the process. 
Here's a screenshot, I have highlighted the menu with a green rectangle: 
Screenshot_20171231-081707.jpg
My SD card is rather old and started malfunctioning recently so I no longer use it with my device. If I did have it or other compatible external storage connected and tapped that menu, it would bring up the options to 'Scan for files' or change between 'Storages'. 
I hope this clears things up.
Best Regards,
Adam @Mixvibes
 
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