I suspect that you are inserting them as citations and not first inserting a “footnote” and putting the endnote citation in the footnote? Word handles the numbering.
If you just insert them as “citations” – they just put in the number with that specific output style and only create what you call “endnotes” which is really the bibliography. If you contact support - they may have a Macro that will convert endnote inserted citations into footnotes.
There are also a couple of Macros made by users. I think this one was the most recent:
https://community.endnote.com/t5/EndNote-How-To/Converting-in-text-citations-to-footnotes-endnotes/m-p/59188/highlight/true#M11004
To contact Technical Support directly
1-800-336-4474 option 4 then 1
or
https://endnote.com/contact/