Also on the banner flying above your city, castle and plastered all over the lords hall and walls.
There's 2 types of helraldic surcoats, one is listed as I've written it and it will change to show your's and the other I think says surcoat w/helraldy on it and it won't show on it.
On mine, if the surcoat or shield is a quartered green and black then that's the one that works. The metal or red and black shields don't change. Also I'm playing the Native Improved Mod and the Nord's Viking Shields (which have symbols on them) will change.
If you're using stock banner symbols then they'll be centered correctly on the surcoat or shield. If you've imported one as I did you have to size and position it just right. As it is, mine loses part of the symbols top on certain shields.