Keyboard malfunction after iMac upgrade today to OS Monterey 12.2.1

Please restart the computer in Safe Mode per the directions in the  How to use safe mode on your Mac - Apple Support link. 

Note: If you are using a wireless keyboard please either plug it in using the supplied Lightning cable that shipped with it. If you are using a legacy keyboard or a third-party keyboard that does not have re-charging abilities, please use any USB keyboard. Also note that a Safe Mode restart may require you to hold down the shift key for up to 5 minutes before the computer starts in Safe Mode. You will know it is in Safe Mode when you see “Safe Mode” in the upper right of the display.

After restarting in Safe Mode, then restart normally and test.

The best antivirus, cleaning app, and overall maintenance app for Mac OS is Mac OS itself. All you need to do with Mac OS to keep it secure and running well is to keep it up-to-date and do periodic (about 1x per week) restarts. Other than that, leave it alone. Adding third party antivirus, cleaning, security and other types of maintenance apps to Mac OS adds no additional level of security. The only thing these apps do is have the opposite affect users want. They make Mac OS slow, unstable, generate odd behavior (much like you are experiencing) and make Mac OS appear buggy. 

• Please locate the developers uninstall instructions for CleanMyMac and follow to the letter.
• Next download and run the free version of Malwarebytes as you have some adware installed that could be causing your problem.
• Then restart in Safe Mode per the directions in Use safe mode to isolate issues with your Mac and then restart normally. 

It will help us get a good idea of what is causing your problem if you provide a report of your system, that way we do not have to play 20 questions with you. The report we are requesting does NOT provide any personal information and is extremely safe to use. Please navigate to www.Etrecheck.com and download the free version of EtreCheck. Once you have you downloaded the app and installed it, please run the report and save it. This report will help us get a good idea what has been installed on your system and help us be able to diagnose what may be wrong.

When you have your report, you can attach it when you reply to this message and we can then review it and help you determine what is needed to get your system running well again.

For instructions on how to download your EtreCheck report and attach it to your reply to this message please click How to use the Add Text Feature When Post… - Apple Community

71Megan wrote: when I try to type an email, holding down any of these 11 keys does not cause the letter to repeat. Instead, I get a pop-up menu showing me similar letters used in foreign languages, asking me to type the number under the foreign letter I desire to use. All 11 of those letters produce some sort of pop-up with similar letters in foreign languages. I have never had this happen in 14 years of using iMacs.

That really is extremely weird, because ever since MacOS 10.7 Lion in 2011, the default behavior for everyone has normally been the pop-up menu, and the only way to get keys to repeat has been to open Terminal app and type in the command (with "false") you mentioned elsewhere. Why that did not affect you until now is a mystery!

Yes go ahead, it works on my M1 iMac

To reverse the change paste this into Terminal press enter and then restart the computer.

defaults write -g ApplePressAndHoldEnabled -bool true

Your welcome. You can find their uninstall instruction on their website.