Keep it out of the sun, it likes shade, some put theirs in a cardboard box if it's real sunny, if the light is straight overhead it works best, early morning or late evening slanting sun rays drive them crazy and even with the screens.
Make sure you set it up at max distance, muzzle blast can wig it out too. If you can find small wooden dowel rods use them to hold the screens that way if you shoot them it won't knock the Chrony off the stand.
I like to use a steel retractable measuring tape to set the distance to the unit you can place one end under your sand bags and run the other out to the unit, then you can see if the tape is level and set the distance above the sky screens, it not only helps to get the distance but it keeps you from shooting the unit.
Mine is a good unit even though it's a little light sensitive, I've shot arrows, pellets, handgun and rifle ammo over it but I wouldn't trust my shot gunning skills !