I've been a 2checkout customer, and am used to the old interface at: https://sellers.2checkout.com/cgi-bin/sellersarea/login.pl. Recently, I've signed up for a new account, and my new seller ID is above 200000, which directs my account to the new interface at: https://www2.2checkout.com/2co/login. The features of the new system look as though they are meant to be a lot easier to use.
But since I'm used to the old Passback Parameters on the: > Account Details > Return (Edit) page, I can't figure out where to put the equivalent "cartpurchase.2c, and Overall Passback parameters" in the new system. Is anyone familar with this?