When you make changes to item data (title, author, date, etc.) in your Zotero library, those changes will be reflected in citations to those items in your word processor the next time you use the Zotero plugin's Refresh button.

If your citations are flat text and aren't being detected at all, see Existing Citations Not Detected.

If you still have active citations (e.g., highlighted in gray when you click on them in Word or LibreOffice, or showing the “Edit in Zotero” popup in Google Docs) but changes aren't being reflected, the citation in your document is no longer linked to the item in your Zotero library. This can happen for a number of reasons:

1. Having duplicate items in your library, citing one of the duplicates, and then deleting it rather than merging items
2. Deleting an item from your library and then reimporting it
3. Citing an item with Mendeley and then editing the document with Zotero (though Zotero can relink Mendeley Desktop citations after you import your Mendeley library)

You can check whether a citation is still linked to your library by clicking the citation in the document, clicking Add/Edit Citation, clicking the blue bubble in the citation dialog, and looking for the “Open in My Library [or the group library name]” button in the popup:

If you have orphaned citations in your document, you will need to delete them from your document and reinsert them, being sure to select from the library section of the citation dialog search results rather than from the Cited section.