When I do an operation like
Several results are shown with an unpleasant background color, how could I change so that this unpleasant background color changes?
It's basically because the permission of the file. Your folder has green background and blue foreground which means that dir is other-writeable(o+w) and not sticky.
If you want to know the color represent what the file type is, you can print
dircolors to a file, like this:
dircolors -p > ~/.dircolors
Back to your problem, to change the color of that dir you can remove the write permission of the others group:
chmod -R o-w redentor
You surely want to remove the background color of all dirs inside
redentor too, so
-R helps you do that recursively.