In the Web Terminal as a Web Admin
To avoid certain information or private information such as phone numbers or email addresses for each ministry being seen by all of your volunteers, when building a roster for a particular ministry, configure the roster to be accessible by "Web Admins and volunteers logged into the Web Terminal", then select "But only volunteers in one of the included ministries":
This way, only volunteers who are qualified to serve in at least one of the ministries included in this roster will be able to view the roster.
In the MSP desktop software
If you are creating a Live Roster Post in the MSP desktop software, go to the Document Settings section in the Rosterizer and check the option that says, "Hide from volunteers not qualified for listed ministries."