RE: The IRS sent me a packet of W-2/W-3C's, I have made the corrections manually and when I go to print them there is not an option to print them on pre-printed/blank forms. Why?! Am I missing something?

No, you're not missing anything. QuickBooks only prints them on plain paper, not on pre-printed forms.

As with W-2 forms, there is no reason to use the pre-printed W-2C forms because the SSA accepts them when they are printed on plain paper.  Printing on forms just makes it harder.