Well, that is why many NLT clients become their own trustees.  If you are your own trustee, then you do all the signing on your own expenditures.  Or the other way you do it is you have yourself appointed as the manager. You either have yourself appointed as the trustee or the manager.  If you are the manager, then the trustee authorizes you to take care of the daily operation of the trust, which includes holding the checkbook, the password login, the debit cards, and the authority to send bank wires, etc.
The less involved way that it is done is to give the trustees a Letter of Wishes every time you want money to be sent out or transactions done.  Since that is inconvenient, it is usually done infrequently by those who have that arrangement.  For example, you could have the trust turn over certain amounts of money to you periodically via a Letter of Wishes, and then you make your expenditures and transactions.  You could even have the trustees approve an ongoing automatic transfer of money monthly or quarterly to you.  Hence they could put it on autopilot - - in fulfillment of your Letter of Wishes only once - - but the autopilot would generate the transfers on a regular basis whenever you have specified.
But the more direct way is for you to be the trustee, or for you to be the manager appointed by the trustees to manage the daily affairs of the banking and so on for the trust.  It all depends upon how hands-on you want to be, how active you want to be, and how frequently you believe you will be creating transactions.