When a user uses a monitor to connect to a Mac device, the system sometimes fails to display the correct resolution. For example, if you're using an old Dell monitor to connect to the new MacBook Pro you just bought, the screen resolution may only be 1280x768 one option. If you want to solve this problem, then you must look at the small writing of this tutorial.
The cause of this problem is usually not the display hardware itself, but the EDID (extended display recognition data) configuration. EDID is a way for the display to tell the computer's video card the best format for graphics display, but some monitors cannot correctly list their native resolutions. This time, if the computer graphics card does not overwrite this value, then you can only use 1280x768 or 1360x765 such a base resolution.
To solve this problem, you can go to the System Preferences display and click "Zoom". In the window below, you'll see all the resolutions the video card can output, and then choose 2560x1440.