Basically what I'm asking is to find a way to disable this option by default rather having it enabled by default. I would rather have the posters choose to have their signatures displayed or not rather having it displayed by default. This includes the regular posting/new topic screen as well as the fast reply screen (you don't see the option like on the full page, but it still adds signatures by default).

Any chance on knowing what file affects this?

Not in the feedback forum there isn't ;)

Try the IPB Peer to Peer forum.