In Testing: Fine grained controls
Over the years, the Iceni's hierarchical grouping system has proved itself to be extremely flexible and easy to understand. You can read more about the group configuration system in the knowledgebase article. However, it has always been limited in how fine-grained the configuration can be - since the configuration is applied to whole groups, adjusting the configuration for a single user required a group to be created just for that user.
We've got a few improvements to the groups system in the pipeline, and the first of those has now entered the pre-release testing phase - fine grained per-user and per-network controls.
Once this is released, you will be able to right-click a group, select "Show users / networks" and then set the usual per-group settings on an individual user or network within that group.