Please could the developers provide different colours for night mode. As a night driver the brown is poor tbh. One can edit the colours I believe but I don't want to mess up. Day mode colours are too bright even if the brightness is reduced. Perhaps the night colours could be chosen from what Here maps and Navmii use which are a fairly good choice.
When I did the download and tapped on the file in Downloads it did not offer Navigator as an option. When I tapped on the file in Total Commander I was given the option Open with Navigator, and then to choose whether set as Day, Night, or just Import. The imported scheme could then be found as Tomas says.
Download seems to be in the standard download folder of the browser, so Mapfactor will not find it immediately. I had to "open" (tap on it) it from the download list of the browser and was asked, which app I wanted to use. When I selected Mapfactor I could find it only afterwards using the settings path @tomas mentions above.
Thanks all. Just tried 486game, Blue Night, Dark Night and High Contrast. All are an improvement on the brown i think. As john_percy mentioned Total Commander i used it... after finding 'my files' didn't provide the 'open with' dialogue.
The next update i hope will include these themes by default... if I had known they existing in the link i would have tried them earlier. Editing one's own is quite a long exercise from what i could deduce.
However the smartphone screen is bright compared with a satnav like garmin for a pro driver in a cab for 10-12 hours even after turning down the brightness in phone settings.