To get started head over to the company settings section:
To access this from your Dashboard, select your company name in the top right corner, and select "My company"
Enter your address in the boxes provided
Any changes you make here are automatically saved and will be added to any proposals and invoices going forward.
From the App:
Click on your company logo to access the menu
Click on "My company"
Click on "Company info"
Edit your company address as needed, and click "Save"