Part of my grandparents know about Bitcoin too. It took a while and many questions for them to understand how it exactly works, but now they know what Bitcoin is and that's awesome. However, it's bad that they do not trust it
you know, the elders usually like real things, the ones that you can touch and hold in your hand, not numbers on a screen.
They are based on their past experience and they aren't alone who don't trust bitcoin, they don't trust online/digital things too.
Because bitcoin is not something that can be touched elders don't trust them as much as we do.