The users shown in the list when adding a moderator isn't complete.
so had to use the "search user" function.

when I found the user
I check the box
and click on the button " Add Selected users".

nothing happens after that.
the button does nothing. and I can't add users with names that ended alphabetically behind.

and also, I can't remove the moderators added.

using cbb 3.08

If you have a lot of users, the list is truncated and you have to use the search function.
Either way when you select a user in the popup and click on add user it should add at the end to the multiselection box of the moderators.
Make sure the new moderator is selected as well (Press the Ctrl key while clicking on it).
Then click on save to store the new forum properties.
To delete a moderator:
- Unselect it from the multiselection box and save.
or
- Select it and click erase. Then select all the remaining and click save.