Changing Hawtio Web Console password does not work

Hi, I've just downloaded ActiveMQ 5.9.0 and install it as a Linux Service on
an Amazon EC2 32bits machine.

I have an access to the Hawtio Web console and can login using the admin /
admin credentials as explained on the ActiveMQ Web Site :

Because having admin / admin as credentials is not really secure I want to
change them. But changing the credentials inside the
conf/jetty-realm.properties file does not work.

For example using the following configuration :

# Defines users that can access the web (console, demo, etc.)
# username: password [,rolename ...]
admin: aaaa, admin
user: user, user

I'm expecting to being able to login using the admin / aaaa credentials, but
using those credentials simply returns a HTTP 403 error. Oddly this
configuration still allow me to login using the admin / admin credentials.

If I change the conf/jetty-realm.properties file using this same problem (I
can login using admin / admin but not bbbb / aaaa) :

# Defines users that can access the web (console, demo, etc.)
# username: password [,rolename ...]
bbbb: aaaa, admin
user: user, user

My ActiveMQ install is "classical", I've installed it as a Linux service
using the following commands :

sudo bin/activemq setup /etc/default/activemq
INFO: Creating configuration file: /etc/default/activemq
INFO: It's recommend to limit access to '/etc/default/activemq' to the
priviledged user
INFO: (recommended: chown 'root':nogroup '/etc/default/activemq'; chmod
600 '/etc/default/activemq')

sudo chgrp ec2-user /etc/default/activemq
sudo chmod 600 /etc/default/activemq

cd apache-activemq-5.9.0
sudo bin/activemq start

I should point out that each time I changed the credentials I restarted the
server using 'sudo service activemq restart'.

So, do you know what could be the problem ?

Thanks,

Baptiste