Listen to your customers and stop this practice. Nobody wants Yahoo as their search engine ! Being sorry is not being sorry if you do not act on it and change the policy of forcing people to repeat the same steps over and over for corporate wins (yahoo probably pays you to do this).
Either quit it altogether or make an option available to never change the default browser. It's that simple.
I have had McAfee for over a decade, but this switching is annoying and since I get spam pop-ups from McAfee I am definitely thinking of leaving. I don't need pop-ups months ahead of my subscription renewal "reminding" me of that. Way to alienate your customers.