I have a Lenovo Yoga tablet YT3-X50F (Android 5.1 Lollipop). I use Firefox as my main browser. I have told Firefox not to remember logins and to clear history after shutdown, but whenever I return to sites previously used (even if I cleared history and cookies just before going to them) the login name or email address, depending on which the site uses, shows in the username box. It is not storing passwords.
On another, earlier Android tablet, I remember there being something in the settings where I had to tell Android not to store logins as well, but I can't find that on this version / device.
How can I stop it doing this?