Hi,
I tested it in Version 1.12.2 (Beta).
The settings (Track linestyle, width and color) only affect following imports - changing the setting does not affect tracks already imported (Kurviger file) and shown as overlay.
I do not know if it is a bug or a feature, advantage: I can show several routes as overlay with different colors: Import 1st route, change color, import next route and so on…
Example: Green and yellow overlay:
Regards Markus