If you want to show your featured images in blog in the original aspect ratio (scale images, instead of hard crop):
- Edit functions.php file in theme folder by FTP (/wp-content/themes/your-theme-name/functions.php).
- Search for add_image_size text in code, you will find theme images sizes code like this:
- Change ALL true words to false in this part of code. This will disable crop for this images sizes in WordPress.
- Save changed file on FTP (or upload it with replace if you edited local theme file).
- Go to WordPress backend, Tools > Thumbnails regeneration and run process. Wait until all images will be resized.