[wenkbt]

my function.php

function change_default_profile_sub_nav() {
    global $bp;
    bp_core_new_nav_default (
        array(
            'parent_slug'       => $bp->profile->slug,
            'subnav_slug'       => 'details',
            'screen_function'   => 'change_default_profile_sub_nav'
        )
    );
}
add_action( 'bp_setup_nav', 'change_default_profile_sub_nav', 20 );