Blogs: Show more than two blog posts in the sidebar

To increase the number of previous posts shown in the sidebar, you can make this modification. 

How to:

Open your Code Editor. 

From your list of themes, find the Actions link for the theme you'd like to edit. Then select Edit code. Example draft theme:

Example if you're working from your main live/published theme:

In the Sections folder, open article.liquid:

Quick link if the theme is live/published:
Open Code Editor

In the code area, use the Find feature (Command-F on Mac, Control-F in Windows) and search for (1):

article_limit

Once you find the first result (2):

Modify the value from 2 to your preferred number.

Save the file.