Why isn't there a finish or complete button?

Our office works with a lot of the older folks and we get numerous calls a day on how difficult Adobe Sign is to use.

When they have signed the forms, why doesn't the button read as "Complete" or "Finish" 

Instead, it is the same exact words of "Click here to sign" which they had to click in the first place and they don't realize they need to click that to finalize the pages instead they think they've already signed there's nothing left to do.