For each component (in each of your JIRA projects), you can assign the roles and tell the plugin who represents a given role for this particular component. This screen is available in the administration section of your JIRA project:
As you can see, this is a list of components inside this particular project. A component can appear multiple times if you wish it to have resources with multiple roles.
For each component, you ought to select a role, and then the user who has this particular role for this very component. When done, hit Set.