Make sure that the software is up to date. Once you open the software, select "Change a filed return," then select the return that you need to change. Please refer to the screenshots posted below. 

Thank you for choosing TurboTax.

The problem is, that when I do that, there is no option to "Change Return" for my wife.  I _know_ I've filed it already, using TurboTax.  I have the confirmation number and CRA obviously knows about it.  Somehow TurboTax has "forgetten" that it was used to file the original return.  How can I convince it that I just need to REfile?

(I accidentally posted this question to the US forum originally.  There, it was suggested I could go  the forms method and tweak the 1040X to indicate that it was for an amendment.  Can something similar be done with the Canadian forms?)

Thanks.