Hello!,
1. PDF-XChange Pro (Editor Plus) v8.0. 343.0
The background color (of the sticky note) is correct (not bright at all), and is consistent with the established color settings.
2. PDF-XChange Pro (Editor Plus) v9.4. 364.0
The background color (of the sticky note) is too much brightness (this luminosity damages the eyes). In my opinion, this is a mismatch that has occurred from version 9.2 (9.1? not sure) onwards. I haven't since been able to reduce the excess brightness of the sticky note background nor set a gray color background. I had to go back to version 8.0. 343.0.

3.

In either case, thanks for the continuous effort.
Thank you very much in advance and greetings.
Kind regards,
CharlesF.