In order to remove CTRL SHIFT LEFT shortcut in ubuntu 18 LTS, which is used by default in ubuntu to switch workplaces, you need to run following commands:

gsettings set org.gnome.desktop.wm.keybindings switch-to-workspace-left "[]"
gsettings set org.gnome.desktop.wm.keybindings switch-to-workspace-right "[]"

this will eliminate problem in phpstorm and intellij idea, that prevents “Move Caret to previous word” to work properly.