generally, where in cPanel can one set the default page to load?

Dear list-members I am using what I assume is a pretty standard cPanel setup (?) I would like to be able change the mime types/extension so that ".html" gets sent through the PHP interpreter, but I see the cPanel docs say "...(note that you can not alter the system defined mime type values)..". So as a workaround, I need to *at least* be able to change the default file to return to the browser when someone hits my domain (or a subdirectory) without specifying the page in that dir/ to load. I cannot find where in cPanel to set that. The default now is the

standard "index.html".    I want to change it to "index.php".

I realize this is really basic stuff, but I can't find it in my cPanel. Can someone point me to this? -Govinda