For starters, go to Billing which you'll find under your workspace name in the top left corner:

In the Workspace section, click Edit next to Details.

Here you can update the details that appear on future invoices, including:

• Company name
• Address
• Tax ID
• Purchase Order (PO) number

If you are based in the EU, add your VAT number with "EU VAT" as the Tax ID Type — Be sure to include the two-letter country prefix. E.g. "FR" for France, "LV" for Latvia