Please follow the below steps to make the EndNote tab appear in Microsoft Word:
Open the EndNote X9 software from the "Applications: EndNote X9" folder.
Close Word and go to EndNote.
Click the "EndNote" menu and select "Customizer."
Check the box in front of the "Cite While You Write" option.
Click next until the Customizer is finished. Open a library.
Then open Word 2016/2019/365 and check the Ribbon for the EndNote tab. (NOTE: The EndNote CWYW tools no longer appear under the Tools menu; rather appears as a separate tab in Word)
You should now see the EndNote tab in the Ribbon of Word 2016/2019/365. If you are not seeing the EndNote tab, follow the steps listed in the knowledge base link.
