Hello quinju,
Thank you so much for using our theme AcmeBlog. We think that you have to proper setup the images on your blog. Please follow the below instruction to fix those issue.
1. Please Go to Setting > Media or follow this instruction. https://doc.acmethemes.com/acmeblog/#SettingupImageSizes
2. Install the plugin Acme fix Images and follow this instruction. https://doc.acmethemes.com/acmeblog/#Howtomaketheimagesizeasondemo?
Hope this will solve your problem. Please let us know if not work or any problem arise.
Best Regards,
Acme Supports