(1) A debtor or secondary obligor may waive the right to notification of disposition of collateral under s. 679.611 only by an agreement to that effect entered into and authenticated after default.(2) A debtor may waive the right to require disposition of collateral under s. 679.620(5) only by an agreement to that effect entered into and authenticated after default.(3) Except in a consumer-goods transaction, a debtor or secondary obligor may waive the right to redeem collateral under s. 679.623 only by an agreement to that effect entered into and authenticated after default.