problem xdj rr and rekordbox

Hello everybody
I have been using an xdj-rr recently
everything is fine except that, after several searches I don't know:
- how to stop the automatic playing of a song when I go back to the beginning of it
- how to prevent rekordbox from analyzing all my usb keys, my computer is not just for music
- erase the entire collection at once, apparently only piece by piece is possible
here are my requests for now
Thank you all for your help
Patrick