To update your Stripe connected bank account, you'll first want to navigate over to your Seller Settings here: https://www.niftygateway.com/account/seller-settings. From there, select 'Open Dashboard', where you'll be brought to a separate Stripe popout.
Once you're logged in, click your profile icon in the top right and select 'Nifty Gateway LLC' under Payout Details. Within that setting, you'll have the option to update your payout method (you may need to verify your existing card details before making a change).