To do a subscript in Word, the first thing we have to do is write the word all together. Once you have finished writing it, select with your mouse the character that you want to put as superscript, and then press the combination of keys Control and + .
Another way to do Subscript Using Ribbon Buttons
If these key combinations don’t work on your PC, you can also use the Word toolbar. Click on Home button then Subscripts or Superscripts as per your requirement,