Thumbnail editor does not work :(

Hi guys :) Please I am new in WordPress and I am having some issues with my thumbnail editor. When I try to resize my picture to the feature slider size, it does not work :(. I tried everything already, but my picture still in the original size. The first slide picture works fine, but the second still in the smaller version. Has anyone had a similar issue? Please, help me! My website is www.catchytrips.com. Many thanks