My b2evolution Version: Not Entered

At the comment pat as registered user

It display like below

Member:
Demo

However I want to display

Member: Demo

I tried to modify code below,

if( is_logged_in() )
{ // User is logged in:
$Form->info_field(T_('Member'),'<strong>'.$current_User->get_preferred_name().'</strong>');
}

However I don't know how to modify.
Any one can help to modify these ?