Information on finding your Product ID can be found here.
Changing Font & Styling:
You can customize the price widget through the Text Panel. Change the font, font color, size, etc.
Check the box beside ‘Customize the decimal and the currency characters’ to enable customization. Now you will be able to change the font size, color, and the vertical position of the decimal (top or bottom).
How to Change Currency:
To change the currency, login to your Shopify store, go to Settings, General, scroll down to "Standards and formats", and then you can select your currency from the "currency" dropdown. Click save to confirm your changes.