Screenwriter deals with text formatting—Bold/Underline/Italics /Strikethrough—by placing hidden format codes surrounding the formatted text. One code starts the format, another ends it.
In normal use, you won't need to be aware of these codes. Screenwriter's default is to Hide Format Codes. To display or hide the codes, under the View menu, select Show Format Codes (OPTION+F3).
A checkmark appears next to it, reminding you it's on.
