[horde] How to set quota format

[Lukas Engler]

Hi,
I would like to change the quota format from the default short to the  
long format. This is a snippet of my backends.local.php but so far  
nothing changed, it still shows the short format. What am I doing wrong?
Using imp 6.1.2

'quota' => array(
         'driver' => 'imap',
         'params' => array(
             'hide_when_unlimited' => false,
             'format' => array('long'),
             'unit' => 'GB'
         )
     ),

King regards Lukas