When I connect to PC to charge occasionally the nexus will ask if I want to just charge the tablet or additionally transfer files. I haven't seen that option for quite some time now. The PC thinks I have no files on Nexus! I know that the answer to my question is to find that option. When I get that I can move files easily with any of the 3 cables that I have. Have trawled the internet and the answer seems obvious. They say go Settings Storage Menu. However for me I go Settings Storage&USB but after that I cannot see a Menu option. The 3 dots top right are what I would assume to be a menu icon however all that gives me is 'Help&Support'. Any thoughts please folks? (Android 6.0.1)