If you are using multiple monitors, select the one to record. You'll recognize this button by its window-like outline with a circle near the bottom right corner.
Press the fourth button from the right – doing so sends the instructions to record the entire screen. These include capturing a still image, a section of the screen, an entire screen, or a window. Press Shift + Cmd + 5 – an onscreen menu will pop up, giving you access to different recording options. Here’s how to record a streaming video on your Mac with audio:
