When you visit a website your browser stores the images from each page in its cache. If you then revisit a page your browser will use the image from its cache (rather than downloading it again from the website) to display the page. That speeds up the display of pages.
However, if an image changes on a website in between your visits to it, you can end up seeing the old image rather than the new one. In order to fix the problem you need to clear the cache. Instructions are here:
http://www.wikihow.co...our-Browser%27s-Cache
However your problem isn't related to your browser's cache. (If it was, you might still be seeing the old 'two jelly babies' avatar but others, like me, would see you new avatar. Since I'm still seeing the 'jelly babies', the problem must be elsewhere).
By far the biggest problem that people have with Gravatar is related to the use of different email addresses. Click on 'My Profile' and then on 'Edit My Profile'. That will show which email address AB has for you. The email address you use on Gravatar MUST be the SAME address as that one. If it's not, your avatar won't appear here.
Chris