Trisquel netbook (mini) version

I discovered this version is very suitable for my Asus eeepc netbook. It is running smoothly without hick-ups.

There is one issue that I want to have solved however and I am not sure how to do it.

I noticed that applications like for instance the update manager and synaptic are not granted SU rights and there is also not a password box popping up to ask for a password. As a result these apps start and die silently.

How can I make sure a login popup is shown when started? (the same behavior as synaptic and the update manager in Ubuntu)

Thank you