Make the selection highlight color the same as chosen in the OS system preferences
The selection highlight color (the color that appears when you select text, etc.) is significantly lighter than the color I chose in my Mac's System Preferences. It's so washed out that the default color options are barely visible, making it appear that selecting text is not functioning. But in the file selection menus (the one that comes up when you open Word or go to File > Open Document) the selection highlight color matches my System Preferences choice. Please make the selection highlight color in the document (when you're writing or editing) match the highlight color chosen in System Preferences.
Daniel Holt commented
Word's behavior in this regard is just bizarre. Why on earth would Microsoft override the system-wide color setting for selected text?