As you build your site, you control how things are displayed using Options. Options cover everything from whether an author's name appears, to who is allowed to view an item, to how many entries show in a list.
Default options for a component are set with the Options button on that component's toolbar in the site administrator. They then apply everywhere that component is used.
Those defaults can be overridden further down: an individual article, contact or other item can set its own options, and so can a menu item. The setting closest to what the visitor is actually looking at wins.
If you are happy with how your site looks, leaving everything at its installed defaults is a perfectly good choice. Options are there for when you want to change something specific.