top.php is not processed by apache

apache 2.4
php5.3.29
centos7

Thank you for your continuous support.
Questions are as follows

• top.php not recognized

/var/www/html/xxx/index.php
/var/www/html/xxx/lists.php, etc.
The is processed as a php file.

/var/www/html/xxx/top.php
Only the is not treated as a php file.
You must choose to open or save the file.

Top.php Contents

<?php
phpinfo();
require_once 'common.php';
require_once'config.inc.php';
require_once 'userAuth.php';
display('systemtop.tpl.php');
?>

There are no syntax errors in apachectl-t.

So I tried the following:

• Change top.php to top1.php

Visit localhost/XXX/top.php again
I was forced to open/save the top.php above.
What does top.php mean when it should not exist?

• Tried to change the contents of top.php

Top.php Contents

<?php
phpinfo();
?>

when changing to and accessing localhost/XXX/top.php I was forced to reopen/save it, and when I opened it, I found out

<?php
phpinfo();
require_once 'common.php';
require_once'config.inc.php';
require_once 'userAuth.php';
display('systemtop.tpl.php');
?>

has been downloaded.

Is there a cache or something left?

Please give me advice/pointing/calling/anything.