Change the text of the publish button to Save

Put below code into your theme functions.php and try

function change_publish_button( $translation, $text ) {

    if ( $text == 'Publish...' )     // Your button text
        $text="Save";

    return $text;
}

add_filter( 'gettext', 'change_publish_button', 10, 2 );

This one is worked for me

Hope it will help you!