Regarding Settings for Post

Selecting Also Affect Children will apply the settings to any URL that starts with https://www.windowstechit.com/4237/windows-10-hdmi-audio-not-working/. So if you had a page with the URL https://www.windowstechit.com/4237/windows-10-hdmi-audio-not-working/page1/ and another with the URL https://www.windowstechit.com/4237/windows-10-hdmi-audio-not-working/page2/ The settings would apply to both of those pages.

Override Post Type Settings lets you override the settings you set on the post type page. So if you set something for all pages and want one page to be different you would select override post type settings on that page to stop the post type settings from affecting it.