We’re in the process of updating the documentation for Zotero 5.0. Some documentation may be outdated in the meantime. Thanks for your understanding.
Many of Zotero's features can be customized via the Zotero preferences window.
The preferences in the preference window are divided over the following tabs:
In addition to the preferences shown in the Zotero preferences window, Zotero has a number of hidden preferences that only can be changed by opening about:config under the Advanced tab of Preferences.