This is a huge problem, and I’m glad you’re asking this question.

Old people really really hate feeling like they’re behind in terms of knowledge. “I’m older and so I’m smarter!” is how they raised their children. So, you really need a demo to shock them into being willing to learn and drop the ego. Not to prove them wrong, but to demo how sinister and believable these things are. Don’t make them feel stupid. Show them what they’re up against.

Personally, I would find either a soundboard (Elon Musk might be easy, as tons of scammers use him and Boomers love him) or see if you can find a free or cheap voice clone app and clone your own voice, or one of your parents. Then call them when you know you or your parents will be around so that they are on the call and trusting it’s a loved one, then the loved one is there and not on the phone and aware of what’s going on.

Not only would this shock them into thinking “well, maybe it’s worse than I thought. They already got me once!” But might also give them a story to tell their friends that will help spread the idea.

Then you lay out basic tools and procedures like are suggested here already. Passwords or code words, helpful cards around the house with questions to ask and answers to expect, prompts that urgency is a sign of crime, etc.