I have found that my mother is calmer and less confused when she can play a recorded message I leave for her. The message might be something like, "Hi, Mom, today is Thursday. You've had a good breakfast, Mary is here with you, and I'll see you after lunch." She plays it over and over again. My mother's diagnosis is mild- to moderate- Alzheimer's.
There's no reason these can't be used for signs, reminders, etc. I even made up the Grandma tattoo to put on the little guy's chest. I know there are very simple to use voice memo recorders that probably aren't too hard to use. I also revamped a Grandma teddybear mother's day card to read "Grandma. We love you...so...use your walker."
This walker reminder after a hard fall and ambulance,ER, etc.