Please see
https://www.zotero.org/support/reporting_problems
and
https://www.zotero.org/support/forum_guidelines#etiquette

we can't help you without more information (and won't be terribly inclined to unless you change your tone)

Adam Smith: Thank you for your contribution. Re more information on "no matter what I choose to cite Zotero adds the same citation": So I press (I know press is such a digitally dead word, but there you go) the add/edit citation button (is it a button or is that just another passe word, who knows?) and the Zotero bar opens up and invites me to select a citation from my library which I do and which Zotero appears to permit but when I check back I see that Zotero has inserted not the citation I chose in that instance but for the instance before that. When I check the other citations I find that this particular citation repeats unerringly and exclusively all the way back to citation number 1. I now have one word document and 20 numbered citations where each number refers to same citation. Hows that for more information? As for my tone, well I think it communicates the frustration I feel at having so much of my time wasted. I did enjoy writing this though even if it means I will have to forgo being helped by you. From your tone that might actually be an enriching experience.

adomasven: Thanks for advice. I'm not on MacOS but I did try reinstalling the word plug in on my WindowsOS. That didn't work.

@YvonneBowe, you sure have a privileged tone. @adamsmith is among the most knowledgeable members of the Zotero community and he spends hundreds of hours each year solving other people's problems on these forums. For free.

Did you ever pause to think there are tens of thousands of very happy users of Zotero, and your problem might be unique to your situation or worse, caused by you or something on your computer? We want you to be able to use Zotero and be productive, but your tone is certainly not helping.