[Theme: Themia Lite] Size of pictures on parent blog category

Hi, I’m a new WordPress user and I chose the Themia Lite theme.

I’m posting some news update on my business website.
In the post, I insert a thumbnail picture on the top left corner.

If I click on a specific post, the picture is indeed a nice small image.
My problem is that if I go to the category (where all the posts are listed one after another), each post is illustrated by the picture which is blown to full column size. This takes too much space, but also some of the pictures then look pixelated.

Is there anyway to keep the picture on a specific post but remove it from when the post is listed in its category?

Thanks!

https://www.ads-software.com/extend/themes/themia-lite/