Why full-screen apps open on the wrong monitor

You start a game, video, or presentation and it opens full screen on the monitor you are not using. This often happens after connecting a second screen, using a dock, or changing which display is your main one.

First identify the displays, then check whether the cause is the operating system or the app remembering an old screen. TooLab’s Screens tool shows connected screens, their resolution and scale, and lets you run a color test on any of them.

Identify the monitor the app should use

1. Open the Screens tool on the computer with the problem. Check the listed resolutions and scales to see how many displays the browser can detect.
2. Use the color test on each listed screen in turn. Look at the physical monitors and note which one displays each test, so you can match the screen you want to use with its listing.
3. Open your operating system’s display settings and check which display is marked as the main display. If you need help identifying the numbered displays in Windows, see how to identify which monitor Windows is using.
4. Exit full-screen mode in the problem app. If possible, move its window to the monitor you want, close the app while it is there, and reopen it. Some apps remember the last window position.
5. Look in the app’s display, video, or graphics settings for a monitor choice. If it offers a display list, select the screen you identified and apply the change before entering full-screen mode.

The Screens tool can help you identify the displays, but it cannot move an app or change its full-screen behavior. The next step depends on whether the problem happens in one app or in several.

What the result means

The color test appears on the screen you expected

You have matched the tool’s screen listing to the physical monitor. If the app still opens elsewhere, check the app’s own display choice and the system’s main display setting. The app may remember a monitor from an earlier setup.

The test appears on an unexpected monitor

The display arrangement or the screen you selected may not match your physical setup. Recheck which monitor is which in system display settings. The order of screens in settings describes their position, while the main display setting influences where some apps open.

Several apps open full screen on the wrong display

This points more toward the operating system’s display arrangement or main display choice than one app’s saved preference. Check those settings, then restart the affected apps so they can detect the current setup.

Only one app has the problem

The app may have saved a display selection, window position, or full-screen mode. Check its video or display settings first. If there is no monitor selector, move the window to the preferred screen before closing and reopening it.

How to fix it

1. Move the app before entering full screen. Exit full-screen mode, drag the window to the monitor you want, and then select full screen again. If the app keeps a saved window position, close it while it is on the correct screen and reopen it.
2. Set the preferred display as the main display. In Windows 11, open Settings › System › Display, select the monitor, then turn on Make this my main display. On a Mac, open System Settings › Displays, select the display, and choose Main Display from Use as, if that option is available. Restart the app and check again.
3. Check the display arrangement. In Windows 11, open Settings › System › Display and use Identify to match the numbered displays to your monitors. Arrange the display boxes to match their physical positions. On a Mac, open System Settings › Displays and arrange the display boxes to match your desk. Arrangement affects how the pointer moves between screens, but it does not always override an app’s saved monitor choice.
4. Choose a monitor in the app. Open the app’s display or video settings and look for a screen choice, especially if it lists a monitor by name or resolution. Select the intended display, apply the setting, and restart the app if it asks you to.
5. Reconnect the extra display. Quit the app, disconnect and reconnect the monitor or dock, then launch the app again. A display identifier can change after a cable or dock is moved, leaving an app with an outdated choice.
6. Check how the app handles full screen. If it offers both exclusive full screen and borderless windowed mode, try borderless mode. It fills the screen while behaving more like a regular window, and may follow the monitor where the window is placed. The exact options depend on the app.

Why full-screen mode can change the display

Full-screen apps do not all choose a monitor in the same way. Some use the operating system’s main display. Others open on the screen where their window was last used, or save a monitor choice in their own settings. A game can also remember a display that was connected only during an earlier session.

On macOS, full-screen apps can use a separate Space, which is a desktop area managed by Mission Control. The Displays have separate Spaces option is under System Settings › Desktop & Dock › Mission Control on versions that include it. Changing this option can alter how full-screen apps and other windows behave across displays, but it does not correct an app-specific monitor selection by itself.

If the issue began after changing monitors, docks, or cables, test the current display arrangement first, then reopen the app on the screen you want it to use.