List of default values for the wpmem_user_upload_dir filter

wpmem_user_upload_dir.php

<?php // Ignore this line.

add_filter( 'wpmem_user_upload_dir', 'my_user_upload_dir' );

function my_user_upload_dir( $args ) {
  
  // Change default directory if user ID is "10"
  if ( 10 == $args['user_id'] ) {
    $args['wpmem_dir'] = 'special_dir/',
    $args['user_dir'] = 'special_sub'
  }
  
  // Make sure to return $args.
  return $args;
}

wpmem_user_upload_dir__defaults.php

<?php

$args = array(
	'user_id'   => $user_id,
	'wpmem_dir' => 'wpmembers/',
	'user_dir'  => 'user_files/' . $user_id,
);