A family of Microsoft word processing software products for creating web, email, and print documents.
I'm also having this problem, in notes in Word 2016. I click on the text in any note, and the whole note gets highlighted. Within the highlighted text, I can place the cursor and try to drag, but if I go beyond the next line from where I placed the cursor, the "secondary highlighting" goes all the way back to the beginning of the note. No way to make it not do that.