The Better BibTeX Configuration can be found under the regular Zotero preferences pane, tab ‘Better BibTeX’.
The configuration of Better BibTeX is a little baroque compared to the standard Zotero Bib(La)TeX exporters (which only have hidden preferences). The defaults should just work, but here’s an attempt to describe what they do.
Making any change here will drop your entire export cache. This is usually not a problem unless you have a really large library, but you can read about what is involved here.
default: yes, but try to exclude already-sentence-cased titles
Bib(La)TeX entries must be stored in Title Case; Zotero items are expected to be entered as sentence-case.
With this option on, BBT will try to sentence-case during import. This sentence-casing uses heuristics, no natural language processing is performed, and the results are not perfect.
You can turn this off, but you may then also want to disable Apply title-casing to titles (which has its own problems, see the help entry for that option on this page).
With ‘yes, but try to exclude already-sentence-cased titles’, BBT will attempt to detect titles that are already sentence cased and leave them as-is on import.
Options:
default: minimal
On import, BBT will add case-protection (<span class="nocase">…<span>) to titles that have words in {Braces}.
There’s plenty of bib(la)tex files out there that do this a little overzealously, and you may not like the resulting HTML code in your items, even though this is what the braces mean in bib(la)tex, and Zotero supports it.
If you turn this off, the markup is omitted during import. When you select ‘yes’, all braces that bib(la)tex would interpret as case protection (which is not all of them) are converted to span elements. In minimal mode, the number of span elements is minimized.
Options:
default: no
By default, when scanning for cited items in the aux file, BBT will just generate a note listing all citation keys it cannot find in Zotero. When this option is turned on, BBT will attempt to import such missing items from the bib file that the AUX file being scanned points to.