The sidebar for blogposts (when this option is selected) shows an “About” section and the most recent articles. Learn how to change each one:
It is a single text module. Access the blogposts with sidebar editing area and change the settings as you prefer:
This section uses the Recent Posts With Thumbnails plugin (installed with the theme).
To change the plugin settings, go to Appearance | Widgets and click on the corresponding Widget. For more information on the plugin options, access the official documentation at https://wordpress.org/plugins/recent-posts-widget-with-thumbnails/