For anyone who has had the same issue as Richard, you can amend the name by which you are known (and who can see what part of your profile) by amending your profile page. Go up to the top right hand corner of the screen where is says ‘howdy whatever your user name is’. Hover the cursor over it and a drop down menu appears. Select Profile from that menu. Select Edit. Your profile page will appear and you can amend your user name to whatever you wish. There are various other things you can amend on your profile too – eg photo, cover image etc.
This drop down menu also contains options to check your messages, view your friends, groups, forums, notifications etc.