Cannot change footer text?

The original theme url here ( https://wordpress.org/themes/sornacommerce/ )

The theme working by using WordPress hooks

You can update this file: sornacommerce\inc\theme-hooks.php on line 438 to 497

Otherwise remove the function on the hook like bellow:

remove_action( 'sornacommerce_site_footer_block', 'sornacommerce_site_footer_block' );

Then add new function to the same hook like bellow:

function wpse291732_footer() {
// your function
 }
add_action("sornacommerce_site_footer_block", "wpse291732_footer");

Hope that will be okay !