Set Default Page in Website Panel
To Set Default Pages:
1. Login to your Website Panel.

2. At the center of “User Spaces” area, click on your Hosting Plan name”.
3. Select on “Web Sites” from “Hosting Space Menu”.
4. Next, select on your domain name such as “domain.com”. At “Home Folder” tab, put the default pages that you would like to set. (eg, index.html, index.php, home.html, etc)

Please refer to the following article to know more.
Knowledge Base: How to change password in Website Panel