You car try this...
1 - redirect all users to your domain with or without www .. using .htaccess
Code:
Redirect non-www to www
RewriteCond %{HTTP_HOST} ^yourdomain.com [NC]
RewriteRule ^(.*)$ http://www.yourdomain.com/$1 [L,R=301]
Redirect www to non-www
RewriteCond %{HTTP_HOST} ^www.yourdomain.com [NC]
RewriteRule ^(.*)$ http://yourdomain.com/$1 [L,R=301]
2 - Set this settings like below.
3 - Change cookie prefix via config.sys file.
.