Use this tool to add text anywhere on a document.

Select the Overlay Text button on the right sidebar, then click on the document. 

The Overlay Text Editor appears and you can proceed to enter text into the blue box.  You can change the font type, size, color, and style as needed.

 

Adjust placement of the text by clicking and dragging the directional arrows in the upper left corner of the box.

To revise any Overlay Text on the document, double click on the orange outline box to bring up the Overlay Text Editor.  Make the necessary changes as needed.