By Clicking on Settings in the upper part of the application, you will be able to setup the parameters of the application. This includes changing/adding mark-ups to your quotes (e.g. GST, VAT, freight, etc.) and the currency for the invoices.
To modify the mark-ups, simply click on the sub-menu Tax Rates and modify or add the values you need.
To modify the currency of the invoices, go to Invoice Preferences. You will see a table with Invoices, Quotes, Estimates, Receipts. By clicking on Edit for any of them, you will see the following screen appearing :
This is where you can chose to modify the currency of your invoices (Red circle).
This screen is also where you will be able to customize the payment method, account numbers appearing on your invoices and include online payment should you wish to (Purple circle).