Wait, is the cartwall in its own window? Then try to delete the position.ini file, or at least the "Cartwall" section from it.
Even if you have turned all "remember window position" options (for the main window and the cartwall) off, an existing position.ini file will still be read and processed at startup. This is useful for multi-user environments when you want to have fixed window positions, without allowing the users to modify them. You just arrange the windows as needed and then turn the "remember" options off.
Perhaps the option should rather be labeled "Save window positions" to clarify this point.
It's pretty much like the "Save within desktop files" options for the browsers, event lists and cartwall. If you turn them off, the information will not be included in the .mld files you save - however, if you open an (old) .mld file which still has browser/event/cartwall information inside, it will be restored, regardless of what the current save options are.