Can't change LightDM greeter screen icons/panel size

Hi All
I can’t seem to change icon/panel size using the lightDM GUI using control panel. Does one have to be root in terminal to change it. When I start LightDM from control panel I have to sign is at root but no changes take place when I log out and log back in.
Thanks:
Rich.

try moving the wallpapers or icons to /usr/share/background or /usr/share/icons