Myujth

i created a small plugin for internal usage, with a settings page.
as follows:

<div class="wrap">

<h1><?php echo esc_html(get_admin_page_title()); ?></h1>

<form method="post" name="desite_options" action="options.php">
 <?php
 //Grab all options
 $options = get_option($this->plugin_name);

 // Desite
 $credit = $options['credit'];
 $logo_link = $options['logo_link'];
 $logo_alt = $options['logo_alt'];
 $dashboard_welcome = $options['dashboard_welcome'];
 $acf_settings = $options['acf_settings'];
 $acf_map = $options['acf_map'];
 $acf_map_key = $options['acf_map_key'];
 $ocean_rtl = $options['ocean_rtl'];

?>

<?php
 settings_fields($this->plugin_name);
 do_settings_sections($this->plugin_name);
?>
 <h3>Admin Customization</h3>

 <fieldset>
 <legend class="screen-reader-text">
 <span>Add desite's credit</span>
 </legend>
 <label for="<?php echo $this->plugin_name; ?>-credit">
 <input type="checkbox" id="<?php echo $this->plugin_name; ?>-credit" name="<?php echo $this->plugin_name; ?>[credit]" value="1" <?php checked($credit, 1); ?> />
 <span><?php esc_attr_e('Add desite credit', $this->plugin_name); ?></span>
 </label>
</fieldset>

 <?php submit_button('Save all changes', 'primary','submit', TRUE); ?>

</form>

i have managed to save the selections and sanitize the fields.
i'm having difficulties to run a function when a checkbox is checked.
for example:
i have the following function:

 function remove_footer_admin() 
echo 'Site built for Bhuka Tours by <a href="https://desite.co.il/">DEsite</a>'; 
add_filter('admin_footer_text', 'remove_footer_admin');

what do i need to do in order to execute this function when $credit is checked, and in which file its best?
thanks.