About blog images

In the article record you can upload an image. If so, the default settings show a thumbnail on the "article list" page and an enlargement when you click through to the "main article" page. You can amend the sizes of both by going to Articles > Article settings. You will need to re-upload images if you want your new sizes to apply to images you have already uploaded.
22/05/2015
If you prefer the main article page to show enlargements (rather than thumbnails) then go to the main Section record: Content > Sections > Open up the Blog section > Under 'Show images' select 'Show full sizes' from the dropdown.