Only account admins or project creators can make a cover page field confidential.
If a field contains sensitive information that you want to hide from project members, you can make it a confidential field.
When you are on the cover page form editor, drag and drop a field into the Confidential Fields section on the Project Fields list.
All confidential fields will be at the bottom of the cover page, and highlighted with a red color. Only the project’s admins and selected project members will be able to see the confidential fields. Please check the “Project Team Management” page to see how to grant the permission to see confidential fields to a project member.