Default user group in phpMyAdmin
I came up with my own solution (but if you think this can be done better, please post your option):

In the file /libraries/Menu.class.php I changed ...

        if (isset($cfgRelation['menuswork']) &amp;&amp; $cfgRelation['menuswork']) {


... with

        $groupTable = PMA_Util::backquote($GLOBALS['cfg']['Server']['pmadb']) . "." . PMA_Util::backquote($GLOBALS['cfg']['Server']['usergroups']);
        $userTable = PMA_Util::backquote($GLOBALS['cfg']['Server']['pmadb']) . "." . PMA_Util::backquote($GLOBALS['cfg']['Server']['users']);

        if (!empty($GLOBALS['cfg']['Server']['users']) &amp;&amp; !empty($GLOBALS['cfg']['Server']['usergroups'])) {
            $defaultUserGroup = 'User';
            $all_mysql_users = PMA_queryAsControlUser("SELECT User FROM mysql.user GROUP BY User", false);
            $all_phpma_users = PMA_queryAsControlUser("SELECT username FROM " . $userTable . " WHERE `usergroup` != ''", false);

            if ($all_mysql_users) {
                $default_user_group = PMA_queryAsControlUser("SELECT `usergroup` FROM " . $groupTable . " WHERE `usergroup` LIKE '" . $defaultUserGroup . "' LIMIT 1", false);

                if ($default_user_group) {
                    $default_user_group = $GLOBALS['dbi']-&gt;fetchAssoc($default_user_group);
                    $allPhpmaUsers = array();

                    while ($phpma_user = $GLOBALS['dbi']-&gt;fetchAssoc($all_phpma_users))
                        $allPhpmaUsers[] = $phpma_user['username'];

                    while ($mysql_user = $GLOBALS['dbi']-&gt;fetchAssoc($all_mysql_users)) {
                        if (!in_array($mysql_user['User'], $allPhpmaUsers))
                            PMA_setUserGroup($mysql_user['User'], $default_user_group['usergroup']);
                    }
                }
            }
        }

        if (isset($cfgRelation['menuswork']) &amp;&amp; $cfgRelation['menuswork']) {


And then I replaced ...

        if (isset($cfgRelation['menuswork']) &amp;&amp; $cfgRelation['menuswork']) {
            $groupTable = PMA_Util::backquote($GLOBALS['cfg']['Server']['pmadb'])
                . "."
                . PMA_Util::backquote($GLOBALS['cfg']['Server']['usergroups']);
            $userTable = PMA_Util::backquote($GLOBALS['cfg']['Server']['pmadb'])
                . "." . PMA_Util::backquote($GLOBALS['cfg']['Server']['users']);

            $sql_query = "SELECT `tab` FROM " . $groupTable


... with

        if (isset($cfgRelation['menuswork']) &amp;&amp; $cfgRelation['menuswork']) {
            $sql_query = "SELECT `tab` FROM " . $groupTable


Then I created an user group "Admin" with all rights, put the root user into this Admin group. At last I created an user group "User" with less rights, refreshed the page and all other users had this group. It is important to do this in this order, because otherwise the root user will also get the "User" rights. When this group can't edit user settings, you can't change it back from within phpMyAdmin.