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: [auth:lower][shorttitle3_3][year]
Set the pattern used to generate citation keys. The format of the keys is documented here.
default: yes
If you have deviated from the default citation key format pattern by specifying your own, you may wind up with non-ASCII characters in your citation keys. You can prevent that using the fold function at the appropriate place in your pattern, but checking this checkbox will just apply fold to all your keys.
default: yes
Enable searching on citation keys. Slows down startup on very large libraries. Requires Zotero restart to enable/disable.
default: within each library
Auto-generated (non-pinned) keys automatically get a postfix when they would generate a duplicate. By default, the check for duplicates is restricted to the library/group the item lives in. When set to global, the check will include all libraries/groups, so auto-generated keys would be globally unique. Changing this setting does not affect existign keys - for this you would need to select the items and refresh the keys.
Options:
default: kept (causes key duplicates)
This determines what happens if you pin a key to a value that is already in use in a different reference but not pinned there. Neither are ideal, you just get to pick your poison. If you let BBT change the non-pinned key by adding a postfix character, the citation key changes which could be problematic for existing papers. If you keep the non-pinned key as-is, your library now has duplicate keys.
Options:
default: LaTeX citation
Used for drag-and-drop/quick copy using Better BibTeX citation keys. In the Zotero “Export” pane, choose Better BibTeX Quick Copy as the default export format for quick copy, and choose the desired format for the drag-and-drop citations here.
Options:
default: cite
Used for drag-and-drop/quick copy citations in LaTeX format. Set the desired LaTeX citation command here. If you set this to citep, drag-and-drop citations will yield \citep{key1,key2,...}
default: no
Used for drag-and-drop/quick copy citations in Pandoc format. You can use this option to select whether you want to have these pandoc citations surrounded with brackets or not.
default: using Zotero item key
OrgMode to select items in your library
Options:
default: using Zotero item key
Hyperlink to select items in your library
Options:
default: <not set>
Used for drag-and-drop/quick copy citations in Build your own format. This is going to get pretty technical, sorry.
You can paste a Eta template here. Inside the template, you will find an array it.items, each of which is a serialized Zotero item. To find out what an item looks like inside the template, export some items as BetterBibTeX JSON.
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.