Help with the Smart Recent Posts Widget plugin settings

Hi, I downloaded Smart Recent Posts Widget plugin, and selected the ‘Classic’ mode. It should show me my recent posts as they appear in the Classic template: https://wordpress.org/plugins/smart-recent-posts-widget/
But, no matter what size of thumbnail I choose, it still shows me small, uncenterned, and cut image. Can you help me please? What can I do??