This issue is still open on our side, but we do not know, why that happens. This is really weird because we do not change this actively, only temporarily if this is required to convert files to PDF with the PDF printer. There are some discussions here in the forum, especially in the German version, but this problem is not solved, because it seems, that this problem is not on our site. Some admins reported, that Windows itself is doing some weird things under special conditions and changes the printer. If anybody of you can send me a reproducible instruction so that I can reproduce the change on my site, then I can investigate further. Hope you can?