To swap currency between your wallets, press the Swap button in your wallet tab.
Select the desired currencies. If any currency is not displayed, you will need to first create a wallet for this currency.
Once you select the coin you would like to exchange, you will be shown the minimum swap amount, as well as the maximum swap amount (for iOS users).
The swap rate is updated in the interface every 10 seconds to reflect the market dynamics. If you take a few minutes to think, you may get a slightly different amount of coins than planned.