You can configure the keyboard shortcut to execute a specific action (=menu item) in the dialog which is displayed when you select +. The dialog lists the available actions together with their configured shortcut and their default shortcut.
To assign a (new) keyboard combination for a specific action, select (highlight) the action in the list and click on the button. A small window will pop up, where you can press the key combination which you would like to assign to that action. Note that only F-Keys (F1, F2, ...) can be used without a modifier (Shift, Control, Alt). All other keys need be pressed together with one of the modifier keys.
After you have entered the desired keyboard shortcut, press the button. If the shortcut is already assigned to a different action, you will be prompted, if you want to override that definition. If you select to overwrite the shortcut for the other action, that action will then have no shortcut assigned
To remove a shortcut completely from an action, select (highlight) that action, and click on the button. Once the shortcut has been cleared, the action is no longer accessible through a shortcut (only through the menu).
If you want to reset the shortcut for a single action to its default, select (highlight) the action in the list, and click on the button. To reset all shortcuts click on the button.