I know you have done a few of these steps, but here is the procedure:
When you open the File>Preferences dialog box, you should see the Logo: entry box. Here, if you click the down arrow, you should see the Browse... option appear.
This will likley open in your PC's Documents directory. Using the familiar browse and selection process, you should be able to choose your logo of choice.
To check your logo, run a dummy Battery Test. With your mouse, choose:
(wait a few seconds)
Cancel the "Please Start Engine" dialog
Choose No on the "You have not entered any details..." dialog if you see it.
This should show you a print preview with your logo at the top of the page.
I'll check on best resolution/size for the logo with our Dev team.
If this doesn't answer your question, please let me know,
Technical Author @ Pico Technology UK