How can I make the BuddyPress members directory default to display all my members in alphabetical or

I am running BuddyPress 1.5.6 and the members directory lists the 17 recently active users by default. I want it to list all of my users in alphabetical order by default. It would be ideal if they could be alphabetized by last name too.

I replaced this line of code in my members-loop.php of buddypress:

<?php if ( bp_has_members( bp_ajax_querystring( 'members' ) ) ) : ?>

with this:

<?php if ( bp_has_members( bp_ajax_querystring( 'members' ),'type=alphabetical') ) : ?>

but it did not work...

Any help would be appreciated.