Before swapping to a new currency, you need to add the wallet for this currency to your account:
- Click on the Wallet icon on the top right of the screen
- Select the yellow plus at the bottom right of the screen
- Select the wallet you want to add
- A pop up will ask you to confirm that you want to add that specific currency - select Confirm to proceed (or Cancel to go back to the currencies list).
You'll see the message Wallet added, the currency wanted has now been added to the wallet list.