multisite change name

Hello,

i use multisite configuration of wordpress and i’m unable to change the name of an author …
i tried network activation of the plugin and single site activation and i reach always the same thing :

i can change name but when i press elsewhere the old name comes.

I would be very helpful to find a solution !

thx a lot

fulgence

http://wordpress.org/extend/plugins/co-authors-plus/