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step1：Open MacBook settings

 

 

step2：Click on Displays

 

step2-1：Expanded mode when unchecked    

 

step2-2：Copy mode when checked 

 

step2-3：Expanded mode when unchecked 

 

step2-4：Copy mode when checked 

 

step2-5：Expanded mode when unchecked  

 

step2-6：Copy mode when checked 

 

Step 3: Set the resolution

Step 3-1 Click the “Displays” option and select the display you want to change.

 

Step 3-2 Set the resolution to: 3840x2160

 

 Step 3-3 Select a refresh rate of 60Hz.