Javascript check first checkbox only

I have some code that repeat a multiple times with some checkboxes in it.

What I need is that only the first checkbox should be checked, in the example you see that all checkboxes are checked because I set so in the code, but I only need te first one to be checked.

How can I achieve that with javascript?

I've tried a couple things, but because the checkbox are inside divs I have no idea how to get this working...