You can right click on a title and select transform to Sentence Case (we recommend sentence case, since that will work with all citation styles; you will need to uppercase proper names manually if there are any).
You can convert the contents of the title and publisher fields to either lower or title case by right-clicking the field and using the Transform Text menu
https://www.zotero.org/support/tips_and_tricks
I'll be importing them again from EndnoteX6, they were originally imported from Factiva. If there is a way of fixing CAPS in endnote before I import them back into that Zotero that would be amazing.
https://www.zotero.org/support/tips_and_tricks