How can to display all Elgg members sorted in alphabetical order

By username

Open the file

elgg\mod\members\pages\members\index.php

And change this code

$options = array('type' => 'user', 'full_view' => false);

With this

$dbprefix = elgg_get_config("dbprefix");
$options =array(
"type" => "user",
"full_view" => false,
"limit" => 15,
"joins" => array("JOIN " . $dbprefix . "users_entity u ON e.guid=u.guid"),
"order_by" => "u.username asc",
);

By name

Open the file

elgg\mod\members\pages\members\index.php

And change this code

$options = array('type' => 'user', 'full_view' => false);

With this

$dbprefix = elgg_get_config("dbprefix");
$options =array(
"type" => "user",
"full_view" => false,
"limit" => 15,
"joins" => array("JOIN " . $dbprefix . "users_entity u ON e.guid=u.guid"),
"order_by" => "u.name asc",
);