How do you change error reporting to only show errors in WordPress?

Alternatively you can create a debug logging file for where you can read the errors. Source: http://codex.wordpress.org/Editing_wp-config.php#Configure_Error_Log

/**
 * This will log all errors notices and warnings to a file called debug.log in
 * wp-content (if Apache does not have write permission, you may need to create
 * the file first and set the appropriate permissions (i.e. use 666) ) 
 */

define('WP_DEBUG', true);
define('WP_DEBUG_LOG', true);
define('WP_DEBUG_DISPLAY', false);
@ini_set('display_errors',0);