My wife and I have this well in hand with our aged parents; how to do so lies in realizing that they are all just going into their second childhood and so need guidance from us caring younger ones. It is very satisfying for us to know that some others and the Washington Post are just as caring about keeping our elderly attuned to safe entertainment.
So we make them conform to a routine of only one hour TV per day and they must read for a minimum of 3 hours each day. They are also allowed 1 hour internet time a day. The rest of the time is made up of them doing their chores.
Their reading must be from E-Ink ereaders so that they do not go blind (but we have some doubts about the veracity of that claim as after all these years they do not seem to have been blinded by THAT other thing
). We also make sure that they take part in only those social activities of which we approve, mix with caring people like us, and go to bed before 9pm. If they do not conform to these rules we, for minor offences, make them stand in the naughty corner but for worse cases we have grounded them for a week or more and denied them use of their mobility scooters.
We are sure that our caring for their intellectual lives in this way, rather than letting them do what they may and so go astray, will stand them in very good stead when they mature from second childhood into their nextworldhood in a couple of years.