Step1: Go to the Blocks overview page (Admin > Structure > Block) to configure the blocks on your site. This page allows you to drag-and-drop blocks into different regions as well as reorder the blocks within a region.

Step2: Next to each block you can click "Configure" to change the specific block settings

Master Drupal in 7 hours - Basic Customization - Manage block - Edit block_01
 
Master Drupal in 7 hours - Basic Customization - Manage block - Edit block_02
  • Block title: Allows you to override the default title for the block
  • User, Role, and Page specific visibility: Adjust visibility for block based on user, role or page.
  • Additional settings may also be available, depending on the particular block.

Note that blocks are configured per theme. If you change the theme or enable multiple themes, you will need to configure blocks per theme.