There are 2 carousels - one for Storyboard homepage and one for Media Room homepage.

Positions in carousels are filled by latest Stories (for storyboard) and by News (for Media Room). You can set up what content type is used for automatic filling. See Automatic post type list of checkboxes.

If you select some article from Left list to Right list, you will overwrite one position in carousel. If you select 2 articles, you will fill 2 positions in carousel. Third position is still filled by latest article. So, you can stick some article in carousel even there are 3 more newest articles than your sticked one.

These are 3 examples of visibile parts of image located on the homepage based on the „Vertical anchor“ setting