The code in footer.php of the Ample Theme (the one that is provided here) is:
<div class="copyright-info">
<?php do_action( 'ample_footer_copyright' ); ?>
</div>
So it uses the function ‘ample_footer_copyright’
That function is found in ample/inc/functions.php on line 116:
add_action( 'ample_footer_copyright', 'ample_footer_copyright', 10 );
/**
* Function to show the footer info, copyright information
*/
if ( ! function_exists( 'ample_footer_copyright' ) ) :
function ample_footer_copyright() {
$site_link = '<a href="' . esc_url( home_url( '/' ) ) . '" title="' . esc_attr( get_bloginfo( 'name', 'display' ) ) . '" ><span>' . get_bloginfo( 'name', 'display' ) . '</span></a>';
$wp_link = '<a href="' . 'https://www.ads-software.com' . '" target="_blank" title="' . esc_attr__( 'WordPress', 'ample' ) . '"><span>' . __( 'WordPress', 'ample' ) . '</span></a>';
$tg_link = '<a href="'. 'https://themegrill.com/themes/ample' .'" target="_blank" title="'.esc_attr__( 'ThemeGrill', 'ample' ).'" rel="designer"><span>'.__( 'ThemeGrill', 'ample') .'</span></a>';
$default_footer_value = sprintf( __( 'Copyright © %1$s %2$s.', 'ample' ), date( 'Y' ), $site_link ).' '.sprintf( __( 'Powered by %s.', 'ample' ), $wp_link ).' '.sprintf( __( 'Theme: %1$s by %2$s.', 'ample' ), 'Ample', $tg_link );
$ample_footer_copyright = '<div class="copyright">'.$default_footer_value.'</div>';
echo $ample_footer_copyright;
}
endif;
Your best bet is to discuss with Ample specifically how to override this in your Child Theme.
That said, you can include footer.php in your Child Theme and edit to remove the theme copyright function and add your own or just use your own HTML.