Older gEdit used config files (
%gconf.xml) in the hidden dirs under your
~home . The new gEdit (v. 3.**) uses
dconf/gsettings backend and as such it no longer uses config files to load the editor prefs. You can either use
gsettings (CLI) to change gEdit preferences.
In your case, to disable line-wrap either open a terminal and run:
gsettings set org.gnome.gedit.preferences.editor wrap-mode none
dconf-editor and navigate to org > gnome > gedit > preferences > editor and in the right pane you will see the key
wrap-mode (should be the last one). Click'n'hold on its value to change it to 'none' (or GTK_WRAP_NONE on some systems).