You may hold assets and liabilities in multiple currencies around the world, but in order to get an aggregated view of your net worth you need to set your base currency. This is the currency which will then be used for all reports and visualisations in vaultbox.
To set your base currency, click the Settings cog on the left of the screen, then select Set exchange rates:
Click the edit button next to your Base Currency to load the following screen:
Type the currency you want, then click Save.
Once you have set your base currency, you can set your exchange rates.