Problem Description:
There is no Endnote Cite While You Write option in word [File]-[Options]-[Add-ons].
The solution to this situation does not require reinstalling any software.
Solution
Find the application named [Configure EndNote] in the endnote installation directory, double-click to run, select [configure endnote components], click [Next], check Cite While You Write add-in for Microsoft Office, click [Next], Click Yes to complete the installation.
Open word to see that there are more EndNote tabs in the functional area.
Enjoy it!