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.
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):
Once you find the first result (2):
Modify the value from 2 to your preferred number.
Save the file.