notepad++ highlight colours

For starter, have you tried 'Settings' > 'Style Configuration' and in pop up, find 'Select theme' drop down box. Choose a theme color that suits you. For example, I'm on 'Deep Black'.

At least in notepad++ v6.2.2, some themes, such as Twilight, seem to ignore changes to the "Tag match highlight" and "Tag attribute". Meaning you end up with very hard to read highlight colors on a dark background.

It seems to be some error in the XML file for the theme. If you remove, for example, the "edgeColour" entry (which is set to styleID="0") then Notepad++ appears to parse the later entries properly - so the color changes do take effect.