Hi Hanna_86, welcome on the NS Community!

Does your husband already have an NS subscription? If yes, he can change the bank account number connected to this subscription in his Mijn NS (via the webpage, not via the app) after clicking on ‘My products’.

If you want to change the bank account number for automatic recharging of the balance on the OV-chip card, you can do on the website ov-chipkaart.nl