Help with "Go Back to Forum" checkbox option

added a couple of checkboxes under my quick reply box (one of them being a "Go Back to Forum" checkbox, but whenever I click it, it does not send me to the forums.

I know I'm forgetting to modify some .php, but I have no idea where.... Can anyone help me out?

I've included an attachment of what the quickreply box looks like.

[CinisterDP]

Oh, one other thing.... How can I disable "show signature" by default? it shows up whether or not someone clicks the quick reply checkbox or not... For the life of me, I cannot remember.