functions.php

add_action( 'init', 'custom_remove_footer_credit', 10 );

function custom_remove_footer_credit () {
remove_action( 'storefront_footer', 'storefront_credit', 20 );
add_action( 'storefront_footer', 'custom_storefront_credit', 20 );
}

function custom_storefront_credit() {
?>
<div class="site-info"> 
<?php echo esc_html( apply_filters( 'storefront_copyright_text', $content = '&copy; ' . get_bloginfo( 'name' ) . ' ' . date( 'Y' ) ) ); ?> 
<?php if ( apply_filters( 'storefront_credit_link', true ) ) { ?> 
<br /> <?php printf( __( '%1$s powered by %2$s.', 'storefront' ), 'This sermon gallery and partner program', '<a href="http://preachnet.com" target="_blank" alt="PreachNet Sermon Gallery and Partner Program Builder" title="PreachNet Sermon Gallery and Partner Program Builder" rel="designer">PreachNet.com</a>' ); ?> 
<?php } ?> 
</div><!-- .site-info --> 
<?php }