On Stripe > Account Settings the External Account for Payouts line shows the default bank for your account's default currency (bank name, routing number and masked account number), and the External Accounts panel lists every bank account on file with a Default badge, its status (for example new or verified) and its currency. "No external accounts!" means no bank has been added yet, which is why payouts would be disabled.

Adding, replacing or changing the default bank account is done in your Stripe Express dashboard - click Stripe > Dashboard to open it - not inside Sprwt. The Payouts page's Bank column and each payout's Account Details show which account received a given payout.