Opened another user account, Guest, LXterminal OK. Therefore some setting in my own configuration files.
Found .config>lxterminal>lxterminal.conf - permissions>user/group= "root"?? Looked at same file in Guest, user/group=guest.
Used superuser file manager to change user/group to howard. AOK!
How did I do that?? (Change the user/group to root I mean.)
Thanks Rudge we posted simultaneously. I don't think it would have run as I didn't have the right permissions, but I'm not going to repeat it to find out!