The financial settings can accessed from the Settings panel, which is at the far right of the main menu.
I will now go top-to-bottom an cover all the fields in the Financial Settings.
You can add your TAX / VAT number here so that it would appear later on the invoice.
You can edit the id field by pressing the green Edit button.
This determines your default account currency. It will be shown on local inventory items and orders as well as on purchase orders.
By pressing Edit you can choose your new default currency (existing items currency will no be changed).
You can see or click to add your Stripe integration here, so that you would later be able to accept payments from customers.