Need to Increase Word Press memory

Need to Increase Word Press memory  Edit this file here - wp-includes/default-constants.php

// set memory limits
if ( !defined('WP_MEMORY_LIMIT') ) {
if ( is_multisite() ) {
define('WP_MEMORY_LIMIT', '64M');
} else {
define('WP_MEMORY_LIMIT', '40M');
}
}

change 40 to some other value