In the admin menu under Settings->Payments, the "Credit Card" enabled checkbox will not stay checked.  I have setup my gateway to be Authorize.net and entered in all the necessary info (Login, Transaction key, URL, etc.).

I figured it out!

The inventory system was enabled and I had not set up any stock.  Once I disabled the inventory system, I saw all the available credit cards to select on the "Edit Credit Card" screen.

I am having the same issue as well. I have disabled the inventory, cleared cache on the dnn installation (Host settings) and restarted the application with no results. I tried with IE and FF same results.

I am running Community Edition on localhost

Any ideas?

only option set to true is "Telephone" should I manually enable this option here?

ok, all good....after restarting the application (Host Settings) the options became available in both Shopping Cart and Store Admin.

Quick, question, for the Paypal Express option, what is the signature field for (i keep getting invalid when using this payment option from a user perspective).