You can manage your bank connections via the ‘Transfers Tab’. You have one external bank shared across all Spend and Invest accounts.
Not Spend Enrolled
If you haven’t had a chance to enroll in M1 Spend – you can manage your external bank connection within the Invest tab. You can always find more information on registering for M1 Spend here. Heads up – you have a bank connection per each brokerage account you have.