What "Primary Monitor" Means and Why It Matters
Your primary monitor is the display where your taskbar sits, where new windows open by default, and where your desktop background appears. When you have two or more monitors connected, Windows and macOS treat them differently — one is primary, the others are secondary. Changing which one is primary moves these defaults to a different screen.
You might want to do this if you've added a new monitor that's larger or better positioned, if you've rearranged your desk, or if you're using a laptop and want your external monitor to be the main one instead of the built-in screen. The process takes less than a minute on either operating system.
Key Takeaways
- On Windows, right-click the desktop, select Display Settings, scroll to your monitors, and click the one you want as primary, then check "Make this my main display."
- On macOS, go to System Settings > Displays, click the monitor you want as primary, and drag the white menu bar icon to that display's preview.
- Your primary monitor is where the taskbar (Windows) or menu bar (macOS) appears, and where new windows open by default.
- You can also arrange how your monitors sit relative to each other in the same settings window so your cursor moves naturally between them.
Changing Your Primary Monitor on Windows
Open Settings by pressing Windows key + I, or right-click your desktop and select Display Settings. Scroll down until you see thumbnails of all your connected monitors.
Click the monitor you want to be primary. A blue outline appears around it. Below the monitor list, you'll see a checkbox labeled "Make this my main display." Check that box. Windows applies the change when ready — your taskbar moves to that monitor, and new windows will open there by default.
While you're in Display Settings, you can also arrange your monitors physically. If your monitors sit side by side but Windows thinks the right one is on the left, drag the monitor thumbnails to match your actual desk layout. This makes your cursor move smoothly between screens instead of jumping awkwardly.
Changing Your Primary Monitor on macOS
Go to System Settings (or System Preferences on older macOS versions), then click Displays. You'll see a preview of each monitor you have connected.
Look for a white rectangle with horizontal lines at the top of one of the monitor previews — that's your menu bar, and it marks your current primary display. Click the monitor you want as primary, then drag that white menu bar icon to the top of that monitor's preview. Your menu bar and Dock move to that display, and new windows open there by default.
Like Windows, macOS also lets you arrange your monitor previews to match your desk. Drag the monitor boxes so they sit in the same relative positions as your physical screens. This ensures your cursor moves naturally when you move your mouse to the edge of one screen.
What Changes When You Switch Your Primary Monitor
When you make a monitor primary, three things move: your taskbar or menu bar, your desktop background (if you're using the same background on all monitors), and the default location where new windows open. Your existing windows stay where they are — changing the primary monitor doesn't move anything that's already open.
On Windows, if you have different backgrounds set for each monitor, the background on your new primary monitor becomes visible when ready. On macOS, the Dock moves to your new primary monitor, and any windows you open from Spotlight or Launchpad appear on that screen first.
Arranging Monitors So Your Cursor Moves Smoothly
After you set your primary monitor, check that your monitor arrangement matches your desk. In Windows Display Settings, the monitor thumbnails should sit in the same positions as your physical screens. If your left monitor is actually on the left, the thumbnail should be on the left in the settings window too.
On macOS, do the same thing in System Settings > Displays. Drag the monitor previews until they match your physical setup. If you get this wrong, your cursor will jump to unexpected places when you move your mouse to the edge of a screen, or it won't move between monitors at all.
Test by moving your mouse slowly toward the edge of one monitor. Your cursor should smoothly move to the adjacent monitor. If it doesn't, go back to Display Settings or System Settings and adjust the arrangement.
Troubleshooting: Monitor Won't Change to Primary
If the "Make this my main display" option is grayed out on Windows, or if you can't drag the menu bar on macOS, your monitor may not be fully recognized by your system. Disconnect the monitor, wait 10 seconds, and reconnect it. Then go back to Display Settings or System Settings and try again.
If you're using a laptop with an external monitor and the laptop screen won't become primary, check that both displays are actually connected. On Windows, sometimes a disconnected monitor stays in the settings list. Right-click it and select "Disconnect this display" to remove it, then set your external monitor as primary.
On macOS, if your external monitor doesn't appear in System Settings > Displays, try unplugging the cable, restarting your Mac, and plugging it back in. If it still doesn't show up, the cable or port may be faulty.
Using Different Backgrounds on Each Monitor
On Windows, you can set a different background for each monitor. Right-click your desktop, select Personalize, then go to Background. Choose a picture, and at the bottom you'll see a dropdown for "Choose a fit." Select "Span" to stretch one image across all monitors, or "Fill" to show the same image on each monitor separately. Windows will repeat the image on secondary monitors.
For true per-monitor backgrounds on Windows, you'll need third-party software like DisplayFusion or MultiMonitorTool, which let you set a different image on each screen. macOS doesn't natively support per-monitor backgrounds, but similar third-party tools are available.
Frequently Asked Questions
Does changing the primary monitor affect my open programs?
No. Programs that are already open stay on the monitor they're on. Only new windows and the taskbar or menu bar move to your new primary monitor. If you want to move an existing window, drag its title bar to the other screen.
Can I have two primary monitors?
No. Your operating system requires one primary monitor. However, you can set up your secondary monitors so they behave almost the same way — you can pin programs to them, arrange windows on them, and use them just as much as your primary monitor. The only difference is where the taskbar or menu bar sits.
What if my monitors are different sizes or resolutions?
You can make any monitor primary, regardless of its size or resolution. Your operating system handles the different resolutions automatically. Just pick whichever monitor you want to be primary and follow the steps for your operating system.
Will changing my primary monitor affect my game or video performance?
No. Your graphics card and monitor refresh rate are separate from which monitor is designated as primary. Changing the primary monitor won't affect frame rates or performance in games or video playback.
How do I move my taskbar to a secondary monitor on Windows?
The taskbar always appears on your primary monitor. To move it to a different monitor, you must make that monitor primary using the steps in this guide. There's no way to move the taskbar to a secondary monitor while keeping another monitor primary.