Sidebar Login title font

I have tried to change the ‘before_title’=>'<h2>’, tag in sidebar-login.php to ‘before_title’=>'<h6>’,

The change does not take. When viewing the page using Firebug, I can see that the comparable lines from funtions.php are being used.

I am placing Sidebar login widget in the secondary area of the twentyten sidebar. Does anyone know how I can get the sidebar login widget function used, instead of the regular theme widget? I’d rather not change the core function file.

Thanks

http://wordpress.org/extend/plugins/sidebar-login/