Hay this is adelina smith, we offer free technical support to people who are facing technical issues. How Find Cash app routing number? You need to open the app on your mobile device and navigate to the "Cash" section. From there, select the bank account you want to update and tap on "Replace This Bank." Enter the new routing number and save the changes. Keep in mind that it may take a few days for the new routing number to take effect, and you should update any recurring payments or direct deposits with the new routing number as well.