Cubase 8: My overdub is recording my whole mix

I just upgraded to Cubase 8 from an old version so i am still new to the new set up, but I am trying to overdub on my mix and it is picking up everything else that I recorded on other tracks? I’m sure there is a simple way to fix this I am just not sure how to get it to record just my overdub and not my whole mix! Please help!

Hi,

Could you describe your routing or send a screenshot of the MixConsole window, with Routing tab opened, please?