How conversion works, and when to enter a rate yourself.
Every total in WorthSafe is shown in one currency: the base currency you chose during setup. You can change it in Settings › Preferences, but read the warning below first.
Rates come from exchangerate-api.com and are refreshed periodically. You can see them all, along with when they were last fetched, in Settings › Data › Exchange Rates.
If the app has no rate for a currency you hold, it does not guess. That holding is left out of your totals and the Dashboard tells you how many items are affected.
On the Exchange Rates screen you can type your own rate for any currency — useful if you have a better source, or for a currency whose published rate does not reflect what you can actually get. Overridden rates are marked, and you can reset one back to the fetched value at any time.
The rate service provides today's rates only. If you back-date a value in a foreign currency, the app would otherwise record today's rate against a past date.
To avoid that, open the asset and tap Update Value. When the currency differs from your base currency, an Exchange Rate field appears, pre-filled with today's rate. Look up the rate that applied on the valuation date, type it in, and the value is stored with that rate and dated accordingly.
WorthSafe User Manual