Editing text not in a text box

Good day.

I have text that I am trying to edit within a pdf file that is in use by my company; it's minor adjustments (3-4 letters per line). However, I do not have the original proof that was used to create the document. 

If I choose "edit a pdf" and adobe does not populate a text box for the area I am wanting to edit, how do I work around this?