Featured Image
WHAT IS A FEATURED IMAGE
Featured images are a popular feature in WordPress sites. They can display a visual preview of what your post/product will look like upon opening. Most themes support featured images and automatically select an image from your post to be "featured". However, you can always edit what image you want to be featured.
HOW TO ADD/REPLACE THE FEATURED IMAGE
Within the post editor, scroll to the meta box called featured images on the right-hand side of the screen. You can either select a new image or replace an existing image. You can also either upload from your computer files or from images stored in your MEDIA LIBRARY *files/images uploaded and stored into your WordPress site.
Video showing above-steps: https://d.pr/v/ecBTXE *video has no sound