MacBook with an external monitor, without window chaos

1. Match the arrangement to your desk

Open System Settings → Displays → Arrange. Drag the screens so they sit exactly as they do on your desk, including height: if the monitor sits higher than the laptop, put it higher here. Your pointer then crosses at the edge you expect. Drag the white menu bar onto the screen you want as the main display; new windows and the Dock favour it.

2. Decide how Spaces should work

In System Settings → Desktop & Dock → Mission Control, Displays have separate Spaces is on by default. Each screen then has its own Spaces and its own menu bar, and swiping between Spaces changes only the screen under your pointer. Leave it on unless a tool you use asks you to turn it off.

3. Move windows between screens

• Drag the title bar across. Slow, but always works.
• The green button: hover over a window's green button and choose Move to the other display (macOS 15 Sequoia and later).
• The Window menu: in many apps, Window → Move to the other display.
• A shortcut: Rectangle adds "next display" shortcuts. In Ribbon, ⌃⌥N sends the focused window to the next display's strip.

4. Give each screen the right layout

The two screens are different sizes, so one layout rarely suits both.

• The big monitor can comfortably hold two or three windows side by side. Halves (macOS tiling with Fn⌃← / →) or thirds (Rectangle) work well here.
• The laptop screen fits one main window. Use it for chat, music, a terminal or reference docs.

A scrolling window manager handles both without extra thought. Ribbon gives each display its own strip: on the wide monitor you see several columns at once, on the laptop you see one or two and swipe for the rest. Nothing gets squeezed when you open more windows. There's more on wide screens in window managers for ultrawide monitors.

5. Clamshell mode

To use only the external monitor with the lid closed, connect power and an external keyboard and mouse (or trackpad), then close the lid. The MacBook keeps running and uses only the monitor. Without power connected, many MacBooks sleep when you close the lid.

6. When you unplug

macOS moves windows from the external screen onto the laptop when you disconnect. When you plug back in, most windows return, but not all. Apps that reopen windows themselves sometimes pick the wrong screen, so expect to move a window or two. If you use Ribbon, its session restore puts your columns back in order after a restart.

Common problems and fixes

• The pointer crosses at the wrong edge: the arrangement in Displays doesn't match your desk. Drag the screens to match.
• Text looks blurry on the monitor: in Displays, pick a resolution marked as a scaled option for that monitor, or use a 4K or 5K panel. macOS renders text most sharply at 2× scaling.
• The Dock jumps between screens: the Dock moves to whichever screen you push the pointer against at the bottom edge. Turn on auto-hide, or keep the pointer away from the bottom of the other screen.
• Apps open on the wrong screen: most apps open on the screen they last used. Move the window once and quit the app; it usually remembers.