Hello and welcome to Advanced Installer forums,
Thank you for your interest in Advanced Installer.
In order to achieve what you want you can change the "Background" and "AppLogoIcon" images from "
Themes -> Preview -> More Options" section. Then, you can change the desired images from "Themes ->
Images" tab. Please keep in mind that your new images should have the same size as our default images. Also, you can take a look on our
"How do I change this color?" thread which may be helpful for you.
If you want you can send us your custom "Surface" theme variation and propose it to be implemented in a future Advanced Installer version.
All the best,
Daniel