Chams are attracted to movement, and will watch any animal around them very carefully to determine if they are potential predators.
All my chams stare at me when I walk into their room, but they recognize me, and stop.
If a stranger comes in, they will hide under foliage cover and just stare at them because they don't know if they pose a danger or not.
Don't supplement your jax every feeding.
I give mine plain calcium w/o D3 every other feeding (very lightly dusted), calcium with D3, and a multivitamin once a month.
It's also a very good idea to get him out in real sunshine as much as possible.
Do not put him in direct hot sun, make sure there is shade for him to go.