Open QuickTime Player
Click File
Select New Screen Recording
Click the arrow next to the Record button
Choose the built-in microphone or another audio input
Click Record
Select the area of the screen to record, or click anywhere to record the full screen
Start speaking or playing audio
Click the Stop button in the menu bar when finished
Save the recording when prompted
If you need system audio, install a virtual audio driver or use a screen recording app that supports internal sound
Use macOS Control Center Screen Recording if available and select microphone audio before recording
Check microphone permissions in System Settings if sound is not being captured