How do I by default disable a checkbox but still get this to work?

OK, I know this is probably a basic question but check boxes are still driving me nuts.

I have a single custom checkbox and a corresponding boolean field in the database - checkbox set to the following:

checkbox966×978 67.8 KB

On form submit it works as expect when you check and uncheck the checkbox it stores the correct 0 and 1 in the boolean in the database.

But, I have tried setting the static value to 0 to uncheck the checkbox by default and it no longer adds the correct value to the database when you check it.

What am I doing wrong??

The outcome I want is on form load the checkbox is unchecked, but still add the correct boolean value into the database when you check it is 1 and unchecked is 0.