When you connect two monitors to a PC running Windows 10 PC, each of the displays is automatically assigned a numeric identification code, 1 and 2, based on the port they are connected to. Although it is possible to set which should be the main screen, it is not possible to swap the identification codes "1" and "2" of the monitors, unless the connection cables are reversed.
Some video conferencing and screen sharing software prioritizes the screen ID number over the configuration settings, which sometimes leads to the wrong monitor being used. In order to reverse the identification numbers of the monitors connected to the PC, it is necessary to perform a quick modification of the Windows registry, disconnect both monitors from the computer, then reconnect them following a specific procedure. This article explains how to reverse monitor ID numbers and how to set the primary display on Windows 10.
Steps
Method 1 of 2: Invert the Monitor Identification Numbers
Step 1. Disconnect all monitors from the computer except the main one
To be able to reverse the identification numbers of the screens in Windows, it is necessary to change the video port to which they are connected. However, swapping the ports to which you connect each monitor is not enough, it is also necessary to delete from the registry the identification keys of each monitor in which the relative numbers are stored. This will allow Windows to correctly detect new monitors. Before starting the Windows Registry Editor, disconnect all monitors from the PC except the one set as the primary one.
For example if you are using a laptop to which you have connected a docking station or an external monitor, use the computer's built-in display by disconnecting all other external monitors
Step 2. Launch the registry editor
To perform this step, type the keyword regedit into the search bar or the Windows "Start" menu, then click on the app Registry Editor which will appear in the list of results.
Step 3. Navigate to the HKEY_LOCAL_MACHINE / System / CurrentControlSet / Control / GraphicsDrivers folder in the registry
An easy way to perform this step is to copy the complete address and paste it into the address bar visible at the top of the program window and press the key Enter. Alternatively, follow these instructions:
- Double-click the folder HKEY_LOCAL_MACHINE listed in the left pane of the window;
- Double-click the folder System;
- Double-click the folder CurrentControlSet;
- Double-click the folder Control;
- Double-click the folder GraphicsDrivers.
Step 4. Rename the "Configuration" key to Configuration.old
The concept behind this change is to delete the current key, but not physically, by simply renaming it so that for Windows it doesn't exist. This way you can easily restore it in case something goes wrong. Follow these instructions:
- Click on the "Configuration" folder with the right mouse button. It is listed in the left pane of the window;
- Click on the option Rename;
- Enter the new name Configuration.old;
- Press the button Enter;
- If something does not work correctly (but nothing strange should happen), you can always restore the original key by going back to this point in the registry and renaming the folder "Configuration.old" to "Configuration".
Step 5. Rename the "Connectivity" key to Connectivity.old
Follow these instructions:
- Click on the folder Connectivity with the right mouse button. It is listed in the left pane of the window;
- Click on the option Rename;
- Enter the new name Connectivity.old;
- Press the button Enter;
- Again, if something does not work correctly, you can always restore the original key by going back to this point in the registry and renaming the folder "Connectivity.old" to "Connectivity".
Step 6. Turn off your PC
Do not restart it, in this case you need to turn it off. Click on the Windows "Start" menu, click on the "Shutdown" icon located at the bottom left of the menu, then select the option Shut down the system. As soon as the computer has shut down completely, you can continue reading.
Step 7. Connect to your computer only the monitor you want to be detected as screen number "1"
It is important that this monitor is connected to the video port principal of the PC. If your computer has multiple video ports, connect the display to the first port. This is usually the integrated video port directly on the PC motherboard.
- If you are using a laptop, the integrated display is always detected as display number "1".
- If your PC has multiple video cards, there is no sure way to identify the primary one other than to try to reverse the original order in which the monitors were connected.
- Do not connect the second monitor to the PC for now.
Step 8. Turn on your computer
Press the power button on your laptop or PC case. If the monitor is off, turn it on as well.
Step 9. Click on an empty spot on the desktop with the right mouse button and choose the Display Settings option
The Windows display settings window will appear.
Step 10. Connect the second monitor to the PC
Windows will automatically detect it and install all necessary drivers. After the monitor is detected, you should see two displays within the "Multiple Displays" section of the right window pane. The monitor identified as screen number "1" is the one currently connected to the main video port of the PC, while the one identified as screen number "2" is the monitor you just connected to the computer. If I connected a third monitor, it would automatically be detected as screen number "3" and so on.
- If the second (and / or third) monitor does not appear in the "Display" tab of the "System" section of the Windows Settings app, click the button Detect located in the "Multiple Displays" section to perform the discovery.
- Windows has automatically recreated the registry keys you renamed earlier, so you won't need to make any other changes.
Method 2 of 2: Change the Main Monitor
Step 1. Click on an empty spot on the desktop using the right mouse button
You can click anywhere on the desktop where there are no app icons, programs or other elements. A context menu will be displayed.
Use this method if you are using two monitors and need to change their order and set the one currently identified as secondary to primary
Step 2. Click on the Display Settings option
It is listed at the bottom of the context menu that appears and is characterized by an icon depicting a monitor.
Step 3. Drag the screen icons to order them the way you want
Each monitor connected to the computer is marked with an identification number. Normally one needs to change the order of the monitor icons to make them reflect the real position of the devices. For example, if the screen number "1" is represented by the laptop screen, while the external monitor is screen number "2" and is positioned on the left of the computer, you may need to drag the corresponding icon so that it appears on the left of that of screen number "1".
- If you are not sure which icon corresponds to which screen, click on one of those present, then click on the button Identify. This way the number "1" or "2" will appear in the lower left corner of each monitor.
- If you have made any configuration changes, click on the button Apply to save them.
Step 4. Click on the monitor icon you want to set as the primary display
The device in question will be selected.
Step 5. Scroll down the menu and select the "Set as main screen" checkbox
It is displayed in the "Multiple Displays" section.
- If the check button in question is already selected, it means that the chosen monitor is already set as primary.
- To set another monitor as the main one, first select the corresponding icon and then click on the "Set as main screen" check button.
Step 6. Click the Apply button
It is visible below the "Set as Primary" checkbox. This way the new configuration settings will be saved and applied to the monitors connected to the PC.
