You should override the view in a plugin, but I doubt all dates are run through a central view. This would be a good feature to add though!

This plugin might help you: http://community.elgg.org/plugins/869364/1.8.2/elgg-18-enhanced-friendly-time

It might not already give the date in the format you are looking for. But you can modify the format via the plugin hook used in start.php. It should then use the date format wherever the so called "friendly time" format is used on your site.

Thank you, I'll try this...

something like ==>

<?php
//
    /**        e1715\mod\profile\views\default\river\user\default\profileupdate.php    **/
    $performed_by = get_entity($vars['item']->subject_guid); // $statement->getSubject();
    /**    'profile:river:update' => "
            %s                                updated their profile    ",
            User A, a <Harvard student>        updated their profile
                $School=$performed_by->name
                $School = $performed_by->SchoolMetaDataName        **/
    $School=    $performed_by->SchoolMetaDataName;
    $School=    "?Student`NoWhere?";
    if    ($School==Harvard)
        $School=    ", a Harvard student";
    if    ($School==Cambridge)
        $School=    ", a Cambridge student"
    $School=$performed_by->name.$School;
//
    $url = "<a href=\"{$performed_by->getURL()}\">{$School}</a>";
    $string = sprintf(elgg_echo("profile:river:update"),$url);
?>
<?php
echo $string;
?>

So, I add                
    $School=    $performed_by->SchoolMetaDataName;
    $School=    "?Student`NoWhere?";
    if    ($School==Harvard)
        $School=    ", a Harvard student";
    if    ($School==Cambridge)
        $School=    ", a Cambridge student"
    $School=$performed_by->name.$School;

to the en.php? Or the commented part? What I want to make is that I only have to modify the en.php. Is there any way to do it? With a code that is possible to do this, you are able to make many plugins to make your site better for the users...