Hello daninet,
Out of the 3 options you mention in your original post, the first one is the one we suggest/support (the other two are not recommended). It indeed makes the whole interface look a little blurry, but that's the nature of the upscaling of non-4K-compliant applications.
This is of course just a temporary measure not a final solution, until we introduce full High Resolution support to the Windows version as well. Unfortunately, it is much harder to make that happen on Windows than it is on macOS (nevertheless, we are working on it).
You also mention that in this mode the cursor is unnaturally small. This is because of an issue that surfaced with the Creator's Update. There's a thread about this small cursor issue, you can find out more about it, along with the solution there:
http://archicad-talk.graphisoft.com/viewtopic.php?p=272263
I hope that you can resolve the small cursor issue, and keep working on!
Daniel Alexander Kovacs
Professional Services Consultant
GRAPHISOFT
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