To replace the YaBB Logo, name yours "defaultlogo.png, gif, webp or jpg", any of those 4 extensions will be activated, upload to "yabbfiles/LogoImages/" overwriting the existing files.
The URL & max height for the Logo can be set in forum settings now.
The default logo location is to the right but you can set the logo to left by choosing Default-alt as template header in Template Configuration.
See the Dark & Purple themes