If your community has multiple blog themes, you can select the default for all blogs and optionally disable the ability of blog owners to change their themes.
Navigate to Administration > Applications > Blogs and select the Default Presentation tab:
Select or change the following options:
- Enable Themes - If enabled, allows users who own blogs on your community to select a blog theme from the those available.
- Enable Theme Configuration - If enabled, blog owners can customize their blog theme's options.
- Default Theme - The default theme applied to the blog when a new blog is created.
Click Save to apply your changes.