Final answer:
To change the font color to gray 25% background 2, often found as the 3rd option in the first row under theme colors, one should use the 'Font Color' button in the Font group within the Home tab.
Step-by-step explanation:
The option to change font color in a program like Microsoft Word or PowerPoint is typically found under the Home tab. When you want to alter the text color, including setting it to gray 25% background 2, which is usually the 3rd option in the first row under theme colors, you should select the text you wish to change and then click on the 'Font Color' button in the Font group within the Home tab.