If you’ve already followed the instructions on the blavatar support page then you will probably need to clear you browser cookies and cache as it will automatically remember the old picture. In most browsers this can be found somewhere in the settings. Once you’ve done that restart your browser and check again.
You may need to re-upload the image even if you did so last week. We had some users reporting issues with old favicon, but it should be resolved now.
Please wait 10-15 minutes after upload, then clear your browser cache if you’re still not seeing it.