Hi there!
I got nearly the same question. Well, i wonder about ACP > Configuration > Main Settings > Users
There's the point called "Current Signature Divider" (Control what divides the user's signature from their post)!
But i really can't control, because i want an image instead of plain text.
Tried it out with absolute and relative path, but doesn't works.
Any suggestions to add an image w/o editing php files?
Thank you!
Greetings, Ghostsearcher