How to make the item display a thumbnail when browsing a collection items

I’m new to omeka and I managed to customize it according to my needs, so I downloaded some plugins and imageMagick to make items dispaly as thumbnail image, but unfortunately didn’t get it to work properly.

what I want is to display thumbnail with the item instead of the default thumbnail that I point to in the attached image above.
any help?

If you click test on the ImageMagick directory path in Settings, does it say you have a valid path?

I installed omeka on windows and the test button give invalid path, but it actually the correct path, and when looking for this invalid path message in the omeka forum, it says that on windows it will give this error message however it should work fine, but in my case nothing works correctly.