Restricted rights

I'd like to give rights to administrate CB users to a restricted category of Joomla Users (named manager). I made a group like that
public
-Manager
--Super user

and gave them the rights to administrate the CB component, except for configuration.

My problem is that my "managers" have only access to CB users that belong to the same groups as them. How can I change that ?

They should have same group or below. Did you create the Manager group or did you use Joomlas existing Manager group? Creating a new one will break CBs ability to map back to it and breaks default permissions. Manager by default has no admin access at all though.

Public
- Manager
- - Administrator
- ....
- Super Users

The above is example of default structure. Making your users "Administrator" should give them some backend access automatically, which you can customize further.

Thank you for your answer.
Unfortunately, I don't understand : I had no "Manager" group in my Joomla installation (I don't remember if I deleted it, sorry).
So, I created one.
I gave it all rights, except "super-user", "off-line access" and "access to administration".

My other groups are "under" in the list.

But, with that configuration, my administrators cannot view members of all groups that are "under" in the administrator view of CB. They only access Public group members...

If you had no Manager group then it was deleted. CB will have a hard time understanding what to do with the new group. The best I can suggest is to move your custom Manager group to be under Registered and that should allow it to work as expected.