How to change colour of file in "find in files"?

It depends on your theme and the type of search. Please share your screenshot. My example:

I think the theme and type of search change what it looks like - but i doubt they impact where the setting is.

but i am looking for setting to change this:

Hi Peter,
If the file name in the next line is identical to the one in the previous line, we make it semi-transparent. Unfortunately, there is no setting to control this. We apologize for the inconvenience. 

Ah, I see. That makes sense. I didn't realize the first was a different colour as I can barely see that one either. Is it possible to change the first one?

This color is used in many places in the IDE. Unfortunately, it's impossible to configure the color only in the "Search everywhere". If you are OK with making many UI elements black and contrasting, try creating a custom theme plugin with the following settings:

```

{
  "name": "theme_basics",
  "author": "JetBrains Support",
  "dark": false,
  "editorScheme": "/theme_basics.xml",
  "ui": {
    "Component.infoForeground": "#000000"
    }
  }
}