Welcome to the community, Janis! :grinning_face_with_big_eyes: This is just a hunch, but I think it’s a limitation of the Box viewer used to preview attachments. It’s apparently designed to print PDF files, but not .docx files. You’d have to ask the Box viewer developers about that.
It’s not opening a browser. The Box viewer is an embedded component of the Airtable application, and has no knowledge of your desktop software, so it can’t open Word or any other application you may have installed. Airtable likely has a license to include the viewer, but they have no control over what the viewer can or cannot do.