Open all selected PDFs in one Preview window - macOS High Sierra As of High Sierra, Preview always opens all selected PDFs in single windows for each document. In the preferences menu, there is an option to change this behaviour for images, but not PDFs.

This is a real bummer and makes Preview a lot less useful. What is Apple thinking?

Ok, the real question is: How do we fix this?
You can install Preview 9.0 again from https://github.com/frhd/macOS-Preview9.0.