That requires a new EIN.  you can get one in about five minutes here:

https://www.irs.gov/businesses/small-businesses-self-employed/apply-for-an-employer-identification-n...

Hello Jim,

Sorry I did not make my question more clear.  I already have an EIN for my corporation.  But on Proseries, I still have my Sole Prop firm name and EIN. My question is: how do I change my EIN & firm name to my new corp name & EIN as I want to have that appear on the returns I'm now making.

@dlm9 Try this:  Homebase > Tooks > Options > Firm/Preparer Info > Firm Information 

You cannot change the name of the Firm there as you will see it is greyed out.  to change that section, follow instructions by clicking on that link under the input section in that Firm/Preparer Info box.

For Employer EIN you should be able to add that where indicated.  Make sure to delete your Social Security Number also.