It all depends largely on how you added the Logo/s and where in the first place?
There is a section to add two Logos in Site Administration > Themes > Logos. One is for the Frontpage Header and the other for a smaller Logo which is automatically added to the top Navbar. after Login and displayed on everypage other than the Frontpage (Site home).
Hope this helps?
Hi, oh sorry must have been blind, logo was missing somewhere else ;) thanks a lot!!! Tom