Making specific Text Boldefaced in a TextBox

Question

Hi I currently have a texbox that prints out info to the user when they press diffrent buttons. I was wondering if there was a way to make only some of my text bolded while

Answer 1

Taking jwillmer's excellent example, I made some adjustments because it was coloring the entire error line for me:

    public static void ChangeTextcolor(string textToMark, Color color, RichTextBox richTextBox)
    {
        int startIndex = 0;

        string text = richTextBox.Text;
        startIndex = text.IndexOf(textToMark);

        System.Drawing.Font newFont = new Font("Verdana", 10f, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, 178, false);

        try
        {
            foreach (string line in richTextBox.Lines)
            {
                if (line.Contains(textToMark))
                {
                    richTextBox.Select(startIndex, textToMark.Length);
                    richTextBox.SelectionColor = color;
                    richTextBox.SelectionFont = newFont;
                }
            }
        }
        catch{ }
    }

Also, I added unique tags before and after the text to color to get the text, then removed them.