You can change the position of success and error messages using the {response} tag or by using the mc4wp_form_message_position filter.

Using {response}

To set the position of the messages using the {response} tag, just place it anywhere in your form mark-up.

Using the filter

Valid options for the filter are before or after, which will show the message before or after the form respectively.

add_filter('mc4wp_form_response_position', function() { 
	return 'before'; 
});