Task: I want to move A_short_history_of_Germany pdf file to Internal Storage folder named History Books.
Steps:
Click on the three dots icon of the A_short_history_of_Germany pdf file to view the move option 
Click on the Move to option to move this pdf file 
Click on the Internal storage at the bottom of the screen to view the History Books folder
Click on the History Books folder to select this folder 
Click on the Move here button at the bottom of the screen to move pdf file in this folder