Hi @Akanksha_Pandey Welcome to the community
Exactly which version of Kibana are you using? I ask because the image above is not a very recent version. The version can be found on the Stack Management home screen.
Also I assume you restarted Kibana after you made the change, and you shift reloaded the Kibana App in the browser.
Just FYI, In newer / lastest versions enabling security / TLS is required to use Kibana Alerts.
It is still OK to use some of these older versions... but if you are interested in Kibana alerts a lot of new capabilities have been added since they were Beta.
The current version of the Elastic Stack is 7.13.0