Choose Apple menu > System Preferences, then click Keyboard.
Click Shortcuts, select App Shortcuts, then click Add (+).
Choose an app from the Application pop-up menu. If you want to set the same key combination for a menu command that appears in many apps, choose All Applications.
If the app you want to select does not appear in the list, choose Other and locate it using the Open dialog. Some apps may not allow you to set keyboard shortcuts.
Type the menu command for which you want to set a keyboard shortcut in the Menu Title field.
You must type the command exactly as it appears in the Application menu, including ellipses and any other punctuation. An ellipsis is a special character that looks like three periods. To type an ellipsis, press Option-semicolon, or use the Character Viewer. It may be difficult to know whether the command is written in the menu with a real ellipsis or with three periods, so if one does not work, try the other.
Click in the Keyboard Shortcut field, press the key combination that you want to assign to the menu command, then click Add.
You can’t use each type of key (for example, a letter key) more than once in a key combination.
Quit and restart any apps you’re using for the new keyboard shortcut to take effect.
"Assign your own keyboard shortcuts to menu commands in any OS X app, including Finder. This might be useful if a global shortcut, which works the same with most apps, conflicts with a specific app shortcut. In this case, you could assign a different key combination.
You can only create keyboard shortcuts for existing menu commands. You cannot create keyboard shortcuts for general purpose tasks such as opening an app."