in qa-config.php :
If you wish, you can define QA_COOKIE_DOMAIN so that any cookies created by Q2A are assigned
to a specific domain name, instead of the full domain name of the request by default. This is
useful if you're running multiple Q2A sites on subdomains with a shared user base.
define('QA_COOKIE_DOMAIN', '.example.com'); // be sure to keep the leading period
add your website and save :)