iMac Volume
The volume on my iMac goes to 100% automatically by itself. I constantly have to turn the volume down. How do I stop this?
Question marked as
What year model is your iMac?
see > Identify your iMac model - Apple Support
If it is an Intel iMac, try resetting the NVRAM.
see > Reset NVRAM on your Mac - Apple Support
If the NVRAM doesn't help or if it is a new Silicone iMac, then test a different keyboard.