Theme Horse

Hi preciouskittens,
Ok I will help for you how to create a child theme ?

Inside the theme folder (where your theme file is located (interface-pro)) Create a filer named interface-pro-child.
Inside this interfce-pro-child folder Create 2 file. One is style.css file and the next is functions.php file

under style.css file

/*
 Theme Name:   Interface Pro Child
 Theme URI:    https://www.themehorse.com
 Description:  Interface Theme
 Author:       Themehorse
 Author URI:   https://www.themehorse.com
 Template:     interface.pro
 Text Domain:  interface-child-pro
*/

@import url("../interface-pro/style.css");

/* =Theme customization starts here
-------------------------------------------------------------- */

If you want css customize then you can write css in this style.css file

If you want to modify other functions then you need to unhook functions.
The file is inside theme folder -> inc -> structure -> content-extension.php

First of all you need to identify which file and functions you need to modify. Then after you start coding. I can give you a simple coding with explanation how to unhook. Then after you need to fix it by yourself and still if you are unable then you may hire a developer to fix it.

unhook functions

// Unhook default Thematic functions
function unhook_thematic_functions() {
    // Don't forget the position number if the original function has one

remove_action( 'interface_404_content', 'interface_display_404_page_content', 10 );

}
add_action('init','unhook_thematic_functions');

add_action( 'interface_404_content', 'interface_child_display_404_page_content', 10 );
/**
 * function to show the footer info, copyright information
 */
 
 
function interface_child_display_404_page_content() {      ?>   
<div id="content">
		<header class="entry-header">
			<h1 class="entry-title"><?php _e( 'Error 404-Page NOT Found', 'interface' ); ?></a></h1>
		</header>
		<div class="entry-content clearfix" >
			<p>Thank you</p> 
		</div><!-- .entry-content -->
	</div><!-- #content -->
  <?php 
}

Here this above functions will overrides the files and display thank you when page is not found. It overrides the previous content and display the new. So you can also edit the missing arguments same as it.

Thank you!