Problem with category going to pagination links

I have a website with various categories, but when a visitor in a specific category page click on the page 2-3-4-etc, he see the page 2 of the homepage (with all the categories) not the page 2 of that specific category.

So, in the index.php i use this code

<?php
if(isset($_GET['p']) && file_exists($_GET['p'].'.php')){
    include($_GET['p'].'.php');
}
else{
    include('home.php');
}
?>

in the home.php i use this code

<?php $number = "10"; 
include("cutenews/show_news.php"); 
?>

The link for the category is like that

[url=https://cutephp.com/forum/index.php?category=33]Category 33[/url]

I have already find this topic https://cutephp.com/forum/index.php?showtopic=42476 but i dont have understand if i must only use the code

if(!isset($_REQUEST['subaction']) || empty($_REQUEST['subaction']))
   $category = "3";

or if i have also reinstall cutenews setting specific parameters.