What "monitor number" means and why you might change it
Your operating system assigns each monitor a number when you connect it — typically Monitor 1, Monitor 2, and so on. Windows and Mac use these numbers internally to remember which monitor holds your taskbar, which one opens new windows by default, and where your cursor moves when you reach the edge of the screen. You do not see these numbers in everyday use, but they matter when you have multiple monitors and want to change which one is "primary" — the one that gets your taskbar and opens new applications by default.
Changing your monitor number is really changing which monitor your system treats as primary. This is useful if you upgraded your setup, rearranged your desk, or connected monitors in a different order than before. The process is straightforward on both Windows and Mac, though the steps differ.
Key Takeaways
- Your monitor number reflects the order your system detected them, and changing it means making a different monitor your primary display.
- On Windows, you drag the monitor icon in Settings to reorder them and set which one is primary.
- On Mac, you move the white menu bar to the monitor you want as primary in System Settings.
- Physical cable order does not determine monitor number — your system assigns numbers based on detection order, which you can override in settings.
- After you change your monitor number, your taskbar, menu bar, and default window placement will move to the new primary monitor.
How to change your monitor number on Windows
Open Settings by pressing Windows key + I. Go to System in the left sidebar, then select Display. Scroll down until you see a section labeled Multiple displays or Rearrange your displays. You will see a visual diagram showing your monitors as numbered boxes.
Click and drag the monitor box you want to be primary to the left side of the diagram. The monitor on the far left becomes Monitor 1 and your primary display. Once you have positioned it where you want, scroll down to find the dropdown that says Make this my main display and select the monitor you just moved. Windows will move your taskbar to that monitor and set it as the default location for new windows. Click explore and then Keep changes when Windows asks if you want to keep the new arrangement.
If your monitors are physically arranged differently than the diagram shows, you can adjust the diagram to match your desk layout. This does not change which monitor is primary, but it fixes the direction your cursor moves when you reach the edge of a screen. Drag the monitor boxes in the diagram to match how they sit on your desk — left to right, or stacked vertically.
How to change your monitor number on Mac
Click the Apple menu in the top-left corner and select System Settings. Go to Displays in the sidebar. If you have multiple monitors connected, you will see them listed. Look for the monitor that has a white menu bar across the top — that is your primary display, and it is Monitor 1.
To make a different monitor primary, click on that monitor in the list and look for an option that says Use as main display or a checkbox labeled Make this the main display. Click it. The white menu bar will move to that monitor, and new windows will open on that monitor by default. Your Dock will also move to the new primary monitor if you have it set to appear on the primary display.
If you do not see an explicit option to set a monitor as primary, your Mac may be using the monitor with the menu bar as primary automatically. In that case, you cannot change which monitor is primary through settings — the menu bar position determines it. This is normal on newer Macs.
What happens when you change your monitor number
When you make a monitor primary, your taskbar (Windows) or menu bar and Dock (Mac) move to that monitor. Any applications you open without specifying a location will open on the primary monitor. If you have a screensaver or lock screen enabled, it will display on the primary monitor first. Your system will also remember this choice and restore it the next time you log in, as long as the monitors stay connected in the same order.
Changing your monitor number does not affect the cables, the resolution, the refresh rate, or any other display settings. It only changes which monitor your system treats as the main one. If you want to adjust resolution, brightness, or refresh rate for a specific monitor, those settings remain separate and are not affected by reordering.
Troubleshooting when monitor numbers do not change
If you drag the monitor in the Windows diagram but the taskbar does not move, make sure you also selected the Make this my main display option and clicked explore. Some versions of Windows require both steps. If the setting reverts after you restart, your graphics driver may need an update — go to Device Manager, find your graphics card under Display adapters, right-click it, and select Update driver.
On Mac, if the menu bar does not move when you click Make this the main display, try disconnecting one monitor, restarting your Mac, and reconnecting it. This forces your Mac to re-detect the monitors and reassign their numbers. If you are using an external dock or hub, try connecting your monitors directly to your Mac instead, as some hubs can interfere with display detection.
If one monitor is not appearing in your display settings at all, check that the cable is fully inserted on both ends and that the monitor is powered on. On Windows, right-click the desktop and select Display settings — sometimes a monitor appears there before it shows in the full Settings menu. On Mac, hold Option and click the Apple menu, then select System Information, go to Graphics/Displays, and verify that your monitor is listed there.
Physical monitor placement versus monitor number
Your monitor number is not determined by which cable you plug into your computer or which physical port you use. It is determined by the order your system detects them when it starts up. If you unplug Monitor 2 and plug it into a different port, it will still be Monitor 2 unless you change it in settings. This is why you can rearrange your desk without your system getting confused — the number stays with the monitor, not the port.
The diagram in Windows Display settings lets you tell your system how your monitors are physically arranged, separate from their numbers. You can have Monitor 1 on the right side of your desk and Monitor 2 on the left — the diagram just needs to match your physical layout so your cursor moves the way you expect when you reach the edge of a screen.
Frequently Asked Questions
Can I change which monitor is primary without unplugging anything?
Yes. On Windows, use the Display settings diagram to drag and reorder, then select Make this my main display. On Mac, click the monitor in Displays settings and select Make this the main display. No unplugging needed — the change takes effect when ready.
Will changing my monitor number affect my game or process performance?
No. Monitor number only determines where your taskbar appears and where new windows open. It does not change resolution, refresh rate, or how your graphics card sends data to the monitor. Performance stays the same.
What if I have three monitors and want the middle one to be primary?
On Windows, drag the middle monitor box to the left side of the diagram in Display settings, then select Make this my main display. On Mac, click the middle monitor in Displays and select Make this the main display. The position in the diagram does not matter — only the setting you select.
Do I have to change my monitor number if I add a new monitor?
No. Your new monitor will be assigned a number automatically, and your current primary monitor stays primary unless you change it. You only need to change monitor numbers if you want a different monitor to be primary.
Why does my monitor number keep changing after I restart?
This usually means your monitors are not being detected in the same order each time your computer starts. Try unplugging all monitors, waiting 10 seconds, and plugging them back in the same way each time. On Windows, update your graphics driver. On Mac, restart with all monitors connected and powered on before you log in.