Overview
Create an .htaccess file in your httpdocs directory, or the directory for which you want to change the default, and add the following line:
DirectoryIndex filename.html
Attention
Change filename.html to the file name that you want to use as the default, e.g. home.html, etc.
Linux system is case-sensitive, so Filename.HTML is not the same thing as filename.html.
*** The above information is for reference only, Please seek independent technical advice if found necessary.