This is because the old version is still in the cache of the browser. A web browser (Internet Explorer, Firefox, Google Chrome, ...) saves web pages and images on the hard disk. This allows your computer to load the web page faster on your next visit. If you visit the page, the version on your hard drive is shown and not the live version of your shop.
To solve the problem: view the page and click Refresh or Reload page.
Or use the shortcut keys: F5 or CTRL + R. (Command + R on Mac)
The latest version of the web page is now loaded.
Some web browsers use aggressive cashing: they keep images even after refreshing a page. In this case you can refresh the image yourself: