Create an account for later use selected by default
 

I have guess checkout enabled as I know not everyone wants to make an account but during the checkout there is a box you can tick that's says"Create an account for later use" I want that to be selected by default. If someone does not want to make an account they can un-tick it.
It wouldn't be an issue but I've come across many buyers who didn't realize they checked out as a guess and have tried to login and were unable to. (I've had to go in and register their account in admin)
Any one know how to get that option selected by default?


Thanks