If you’re uploading a new studio logo or invoice logo, but the old logo is still showing up, most likely, the reason is that your browser is pulling from your Internet cache to show the old logo. Other people will see the new one, but you see the old one. This is especially true if you are using Internet Explorer (which is notorious for poor caching), or a web accelerator.
To solve this problem, simply clear your Internet cache. In Internet Explorer, you can do this by going to Tools → Internet Options → Delete Files.
The instructions for Safari can be found on this site: http://support.verio.com/documents/view_article.cfm?doc_id=4069.
For Firefox users, the instructions are found on this site: http://support.mozilla.com/en-US/kb/How%20to%20clear%20the%20cache