.htaccess , internal error and index page

hello

I want to change the index page content of my website, the old page name is index.htm, I have renamed to oldindex.htm and uploaded another file called index.php, but when I navigated to my website, the content didn't change (cash is not the problem, I have opened it from another computer too).

another problem: the new content appears only when I navigate to mysite.com/index.php

I deleted the oldindex.htm and for a certain reason I have uninstalled the FrontPage Extensions, but after this, when I navigated to mysite.com/index.php it gave an error 500 internal error, and the oldest content of index.htm still exist

note: before editing index.htm and uploading the new page there was an .htaccess file which its content was:

# -FrontPage-

Options None

<Limit GET POST>
order deny,allow
deny from all
allow from all
require group authors administrators
</Limit>
<Limit PUT DELETE>
order deny,allow
deny from all
</Limit>
AuthType Basic
AuthName hydraulics-edu.com
AuthUserFile /home/hydra/public_html/_vti_pvt/service.pwd
AuthGroupFile /home/hydra/public_html/_vti_pvt/service.grp

after that, I reinstalled the FrontPage Extensions and:

1. the oldest content of index.htm still exist

2. navigating to mysite.com/index.php requires a username and a password

I am confused, thanks for any advice

It sounds like your web host or your web server has some kind of caching enabled.

thank you Morpheous for your replay

this means I can't update my website, can I do something?, googling "how to disable cache of web server" didn't gave fine results.

thanks

Edit: I am using cPanel