Automatically formats all brackets as an in-text citation.

I have Endnote X9 on my Mac and when using Cite to Write on Word, when I click “update citations and bibliography” it is automatically assigning in-text citation number 1 to some text I have in brackets like these []. How do I prevent it from adding a citation to this bracket?

I suspect your temporaty citation delimiters are set to be square brackets rather than curly brackets.  There are two places you can change this.  One in the endnote program preferences, temporary citiations (for all documents) and the other in the Endnoe configure bibliography settings on endnote ribbon in word  – the two settings dialogues are shown for windows, they will look slightly different on your Mac.