I've very recently installed Ubuntu 14.04 (on a Dell Latitude 640M with XP Professional in a separate partition) and the two symbols @ and " have swapped positions on the keyboard (I chose UK language setup). I have a full size separate Logitech keyboard, and the swapped key fault also occurs on my laptop keyboard.
I tried two fixes suggested in another post: ibus-setup and dconf tool. Ticking the recommended box in the ibus setup didn't have any effect. When I opened the dconf Editor it didn't seem to work as no options come up when I click on any menu items. I tried reinstalling (using Synaptic Device manager) but no change.
Thanks for any help. Finding my way around Ubuntu is a steep learning curve.
Generic | standart PC 101 keys
. Sorry that I can't tell you an exact option, I just have KDE, not Gnome; but I am sure that the Gnome probably have alike option.