If after uploading your picture you are seeing the old version, all you need to do is go to a page where you are seeing your old picture (i.e. to one of your posts) and hit the F5 button on your keyboard.

This will tell your browser to get the latest images from the server.

If you are STILL seeing the old image, then you need to delete your cache.

Click: Tools->Internet Options->Delete Files - then click OK.

Now try refreshing the page. You should now see your new image.