"Prompt for confirmation" disabled most of the time

Hello everyone, i've been using Teamviewer a few years now to help out friends & families with technical issues with their computers, sometimes mobile devices too.

The issue i'm having is that "prompt for confirmation" is almost always disabled, and i have no idea why. It's m;uch easier to tell the person to click "Yes" on the confirmation window, than to get them to open the teamviewer UI, then locate the ID and password, then give me the password without making mistakes.

What factor(s) determine if this authentication mode will be disabled or not??