Can I change the blog posts that show at the bottom of each post?

Additional posts are automatically included, you can adjust the posts that display based on the Post Filter setting

With the POWER Sec Post Preview module, you have the option to change the posts displayed to one of the following:

Based on your choice, additional settings are available.

The post preview section of the blog post is configured individually for each post.

If you change the default settings, create a draft post to use as a template for future posts so you don't have to reconfigure each time.