I also have an issue with the default map doing its own thing.
RadarBox will occasionally open on a map which I don't instantly recall - when I reset to my default map, I find that it's no longer the one I've saved. I haven't mentioned it before, because it seems it's just one of the minor quirks of RadarBox.
DC
In my experience, RadarBox opens at the map view that was last in use. I've been testing the outline for Hong Kong airport, so I shut down Radarbox viewing Hong Kong. When I start it up, this view is what I get - so that's fine for me.
I just click the Home button and I get my home loaction centred in the map.
By the way, I rarely actually load another map, I always use default.ml3 and just scroll, zoom or use the find functions to move around. When I want to got home, I just click Home - simple.
My colour scheme isn't always remembered though, but that is just one click in the colour drop down menu. I really can't loose any sleep over this :-)