Language

Click on Edit and chose “Preferences” to open the “Zotero Preferences” window. Click on the "Advanced" tab. Choose English as language under "General",

Syncing

Click on the tab “Sync”. Enter your Zotero account and chose manual or automatic synchronization. By default, Zotero will sync your data with the Zotero server whenever changes are made. To disable automatic syncing, uncheck the “Sync automatically” checkbox in this section.

Syncing allows you to work with your data from any computer with Zotero installed and it allows you to view your library online on zotero.org. Syncing of descriptions is free and has no storage limit but doesn't sync attached files (PDFs, audio and video files, images et cetera). To sync these files, you can choose “Sync full-text content”. Zotero offers up to 300MB free for storing files. For additional storage space you need to pay.

Citation style

You can determine the way of displaying your descriptions when you export or copy them to text documents. This helps you to be consistent when you use citations which refer to descriptions of sources like books, blogs, videos et cetera.

Click on the tab “Cite”. Choose your preferred style manager e.g. Chicago Manual of Style 17^th edition (author-date).
Click on the tab “Export”. Choose your preferred “Default Output Format”, e.g. Chicago Manual of Style 17^th edition (author-date).

Zotero preferences citation style