As an administrator, you will be able to view/modify visibility settings for Ideas, Campaigns, Portfolios, or Custom Pages in the content's settings. To get there, simply go into your content's settings, and scroll down to the Access section.
Here are some helpful terms related to you content's visibility settings:
• Public (Company Wide) Visibility: Any user at your company can see the content if this setting is selected.
• Workspace Visibility: Any user that belongs to the content selected workspace(s) can see the content if this setting is selected. (e.g. If a user belongs to Company A, but only the Workspace for Company B is selected and Workspace Only visibility is selected for that content, the user from Company A will not be able to see that piece of content).
• Team Visibility: Any user that is selected as a Team Member in the Team section of an Idea, Project, or Portfolio can see that piece of content if this visibility setting is selected.