Confused by colours

I'm new to this..

Some of the windows have red header bars, that turn green or yellow..

Then some of the mimize windows are yellow, or then blue.
Very confusing. Why do they change?

Can these all be set to stay one colour?

The colours indicate the lister state - whether it's a source (green), or destination (orange). The minimized icons indicate whether a lister is single (yellow) or dual (blue).

All these colours can be modified in preferences.

You should watch the MultiListers video.