This is a caching issue which is causing the image not to update. The issue can be resolved by the user in a number of ways:
  1. By clearing your cache (In Internet Explorer, this can be done through Tools > Internet Options. Under Browsing History, click Delete. Next, delete your Temporary Internet Files and Cookies.)
  2. By starting a new browser session
  3. By uploading the new file with a different file name
  4. By using the CMS image library instead of the standard Image Library
Eventually, once the cache is refreshed, the URL should reflect the new image.