When you apply subscript, a predefined baseline shift and type size are applied to the selected text, positioning it below the normal line of type. To apply subscript:
Click the text frame to open the Text editing toolbar.
Select the part of the text, then click Subscript to position it half a character below the normal line.
Note: If you don't select any text, the setting applies to the new text you type in the same text frame.
Save the page when you're done.