Try to switch a display as the main while using multiple screens on the PC, but you couldn’t. And the option ‘Make This My Main Display’ greyed out.
The cause behind the issue is not your device but some settings. You can explore the fixes after reading this article.

How to Activate the ‘Make This My Main Display’ Option
The issue occurs for some display miss settings. You can fix it by following a few processes. Let’s have a glimpse of the fixes before executing.
• Reselect the Main Display
• Update Graphics Driver
• Update Windows
Fix 1: Reselect the Main Display
Most of the users can solve the issue by following the fix. You can also solve it thyself.
Step 1
Go to display settings where from you became evident the issue.
Step 2
Just alternate the display option. For example, if Display 1 is the main display, you have to select Display 2. After a couple of seconds, reselect display 1 as the main display.

Finally, check the option. Is it back to active or still greyed out?
Fix 2: Update Graphics Driver (if needed)
In some cases, you need to update the Graphics Driver. Here I include the process step by step.
Step 1
Firstly, tap the Windows and ‘X’ keys together. You will find ‘Device Manager’. Whenever you see the option, you have to tap it.

Step 2
Consequently, the ‘Device Manager’ interface will appear on the screen. Scroll down and find out the ‘Display adapters’. Once you see it, you have to expand it.

Step 3
Right-click on the option, which one you prefer to make as the main display. Then click on the ‘Update driver’ option.

Fix 3: Update Windows (if needed)
Update windows is a common fix for all types of issues you face while using the Windows Operating System. You can try the fix here too. To do that, you have to check for updates first.
Step 1
Press the Windows and ‘I’ Keys together to open the ‘Settings’ interface.

Step 2
Then you have to click on the ‘Update & Security option. You will find it at the ‘Settings’ bottom line.

Step 3
Next, you have to tap the ‘ option. It will exist under the ‘Window Update’ section.

Step 4
Finally, if any update is available, you need to install it.
Final Words
In a word, you do not need to worry about your devices while the ‘Make This Main Display’ greyed out. Because the issue appears for some miss settings that are easy to fix.