How It Works
PIN can be enabled in the app settings. Once it is enabled, you will be required to enter it every time you open the app after a specified inactivity time. PIN is synced across all of your devices via iCloud Keychain (please make sure that it is enabled in the system settings if you want to sync your PIN). Touch ID can be used in iOS for authentication once PIN is enabled.
How to Restore Forgotten PIN
Please note that a forgotten PIN can be restored only on a Mac that either was used to create the PIN in the first place or is synced to your iCloud account.
1. Open "Keychain Access" app on your Mac. You can use Spotlight to locate it.
2. Search by the word "Debit", make sure that "All Items" is selected in the left sidebar.
3. Look for the keychain item that contains the word "PIN".
4. Right click the item and select "Get Info".
5. Enable "Show Password" option to see your PIN.