The Ever-Changing Menu Bar in OS X El Capitan
Before you start working with OS X El Capitan menus, you really, really should know this: Menu items can change unexpectedly. Why? Well, the menus you see on the menu bar at the top of the screen always reflect the program that’s active at the time.
When you switch from the Finder to a particular program — or from one program to another — the menus change immediately to match whatever program you switched to.
This figure shows the menu bars for the Finder, Preview, and TextEdit applications.
An easy way to tell which program is active is to look at the application menu — it’s the leftmost menu with a name, just to the right of the Apple menu. When you’re in the Finder, of course, the application menu reads Finder. But if you switch to another program (by clicking its icon on the Dock or by clicking any window associated with the program) or launch a new program, that menu changes to the name of the active program.
When you have an application open, the commands on the menu change, too — but just a little bit. What makes this cool is that you have access to some standard application menu items whether you’re running Mail or Safari. For example, most (but not all) applications have Cut, Copy, and Paste commands in their Edit menus, and Open, Save, and Print commands in their File menus.