1. In Edit Account Details > Bank tab > Remove the entries in the 'Default Cash Account' in the bottom grid
  2. Change the 'Account Setup' column to 'Does not use this bank account'.
  3. Click Save and Close.
  4. You will receive a warning that the bank account uses several account codes and this will cause reconciliation issues. Click OK.
  5. In General Ledger, Records, Account, open the appropriate cash account to change.
  6. Change the Account number, Description, etc. as desired.
  7. Save and Close the account number.
  8. In Accounts Payable, Banks, click 'Edit Account Details' for the bank changed in steps 1-4.
  9. On the Bank tab, reset your default cash accounts with the new account number.
  10. Save and Close the bank account.

Note: If  the Account number has been set as the Default cash account for a bank account and there is activity in the account and bank register, the account number cannot be changed, but instead made inactive and a new account number and new bank account must be created. The account activity in the old account number can be transferred via manual journal entries to the new account number.In Accounts Payable, Banks, click 'Edit Account Details' for the bank account associated with the cash account.