Dear LenVH,
This is a browser cache issue. Basically once someone went to the site once, even if the images in the server changed, the user would still see the original images because the image was cached on their computer.
Even you changed the image on the web server, however the browser still load the old image from the local cache.
As a web application, Cute Editor doesn't have the permission to clear your local browser cache.
Thank you for asking