When you answer a question or make a comment publicly, all other users in the Siminar see your answer. You may choose to answer questions privately, in which case only the course facilitators and you can see your answers or comments.
To make a question or comment private, just click the "Public" icon:
You will then get a pop-up message with a selector that lets you set the visibility. Choose the "Visible to Author, Faciltiator & Mentors Only" (you're the Author!). Then click "Set Visibility."
The "Public" will change to "Private" and you can submit your question or comment for the Faciltators and Mentors only.
You will also see these private answers and responses in the community area and your notifications tab because you made them, but others will not.
If a facilitator answers or responds to your private question or comment, only you and the faciltiators will be able to see the response, just like with the original private comment or answer.