ServiceDesk Plus allows you to publish knowledge base solutions as either public (available for all requesters and technicians) or private (accessible only by technicians).
To make a solution public, while adding/editing the solution select the checkbox "Publish this solution in Self-Service Portal also". This will make the solution available to the requesters also. If you do not wish the requester to view any of the solutions, then just leave this check box disabled.
This feature has been implemented as per the industry standards where some of the solutions entered would not be relevant to the requester and hence can be made as private articles.
Also, if there are any repeated support requests for which the resolution is already known, then this can be entered as a public solution in the knowledge base, as it will allow the requesters to resolve the issue themselves and thus help in reducing your support load.