Building on Lorraine’s topic, I often quote sources outside of TuD, like text from a research study. What I do is mark the text in the external source which can be done in variety of ways but I use my trackpad and click and hold with one finger and then drag a finger from my other hand to mark the text. I use the “control + C” to copy that text and then return to the TuD editing window.
I then paste that text with a “control + V” keystroke combination. In order to show that these are not your original words but something quoted from an outside source, mark the pasted text in the TuD edit window and then click this edit window icon: 
The copied text then is shifted to the right and graphically marked with grey highlights. This reinforces the visual look that these words are quoted from somewhere else, like the sample below.
Dec 18, 2017 - Aspirin , or acetylsalicylic acid (ASA), is commonly used as a pain reliever for minor aches and pains and to reduce fever. It is also an …