By default, your reply to setting will be one of these: reply or reply all. If it is set to reply all, then anytime you click the reply arrow at the top of a message , it will reply to everyone on the original email (such as FacultyStaff). Below are steps to change it to fit your preference:
1. Click on gear button (top right of your email) and then settings.
2. On the General tab, scroll down until you see "Default reply behavior."
3. Select either Reply or Reply all, depending on your preference.
4. Click the Save Changes button at the bottom of the page. Your changes have been set and the reply arrow will now default to the setting you selected.