Sometimes you may discover errors in the metadata, e.g., an false year of publication for a source. Never change directly in the citations in the document (grey fields in Word), since all changes made there will be overwritten the next time the document is updated! Instead, do as follows:
Note that the connection cannot be restored! If you break it, it should thus be among the last things you do with the document. We also recommend that you make a copy of the document before breaking the connection; in this way, you will still have a version to work with in Zotero, should you wish, for instance, to change the reference style in your article in order to send it to a different journal.
If an item type is missing fields in the metadata that are needed in the citations and are included in a reference style, you have the possibility to add certain data in the field Extra, found at the bottom of the item metadata.
Add each variable on a separate line in the Extra field according to the following format: [CSL variable]: [value], e.g., "Original date: 1824".
A list of allowed CSL variables can be found at this page.