The string searched is displayed in red by default. In a gray scale display, strings are displayed with 16 red intensity levels. However, in a Windows screen with 256-color mode or lower modes, the colors cannot be accurately represented.
The measures against this are setting the screen to "High color" or "Full color", changing the color assignment to the box shape (Property Sheets->[Search]), or changing the gray scale.
If characters already colored by color specials are found, the colors are not changed. This can be indicated by underlines, boxes, or cursor movements.