Canada - U.S citizen in Canada

Hi, sorry if this is a silly question but I haven't been able to find the answer anywhere:

I'm a U.S. citizen who's been in Canada for two months. I'd like to extend my stay. However, on my declaration card when I entered Canada, I wrote that I'd be staying for 60.

I know legally I can stay for 180. My question is, does it matter what I wrote on the declaration card??

Thank in advance!

Any date written on the stamp in your passport?

You can stay up to 180 days.
Anything more, just leave the country and come back.

If your passport wasn't stamped, or if it was stamped and no date was indicated, you're legal for six months. You can apply to CIC for an extension of status. The fact that you initially indicated an intention to remain for sixty days is likely irrelevant.