Post Loop (PB) problems

Hi

On my webpage https://5270.dk/sats/ i′m using the Post Loop widget on my Homepage.

My problem is that the thumbnail i′m usion in my post, shows up almost perfect on the homepage, but when i click on the image and goes to the post page, the thumbnail is blown up to a massive picture.

I can awoid it by using pages instead, but then it shows all my pages in the Post Loop, and not only those pages i want !

What to do ? Any ideers ?