When changing the logos of UPK deliverables you can change bother the logo for Knowledge Center output and the local player package.
To change the logo for knowledge center you would go into the \Web Sever\KCenter\Images directory find the current oracle logo (small_logo.gif) rename it and paste in the new custom logo and rename it to “small_logo.gif”.
To change the logo for a local player package you will have to locate the “img” for that player package (Publishing Content\PlayerPackage\img) use the same replacement process as you would with changing the Knowledge Center logo.