Checkbox signed instead of checked - how?

I used a checkbox in a PDF. I prepared the PDF for signature using Acrobat Pro DC.

Sent to client and instead of a check in the box, it came back with a signature... WTF?

I see the mistake I made, I think:

The first check box is really a signature box?? When I click 'Preview' it works like a check box.

When I send it out... got a signature back. Super frustrating!

How did I make this mistake, so that I can never make it again!?!

Right-click then Properties on the box doesn't seem to help...

Thanks!