One thing I noticed from your pictures is the screen tops. Screen material is so fine that it filters out the good UVB rays. Setting the light on the screen isn't a good idea. The UVB light needs to shine freely into the tank with no screen.
Need some advice! (mouth injury)
To add to Yvonne’s comments, you also need to remove the plastic cover over the bulb on the hood lamp.
For adults, you can accomplish a fairly good level of humidity just by keeping the substrate moist. I have open top containers that stay in the 70-ish % at turtle level just by adding water to the substrate regularly. The turtles aren't standing in water but the substrate is darkened by the dampness. When the top layer starts to change a lighter color, I pour in more water. Misting is great, recommended, and temporarily boosts humidity, but for humidity control "heavy lifting" use a tea pitcher full of water. Experiment to find the amount of water that gives a good balance between soggy and damp. If you have baby box turtles, the soggier the better. Some people keep them in strictly water based enclosures, no substrate, just an inch or two of water, some hiding places, and some rocks they can climb out on to dry off.
Another option is to use some plastic sheeting to drape over your adult turtle enclosures, lighting and all, to separate them from the air space at large in the house. If you choose this option take care to not let the plastic come in contact with your lighting fixtures as the heat could melt/burn it.
Then there is the mecca of all turtle enclosures: the sealed chamber. It's basically an airtight container that gets its gas exchange when you open it to change water, feed and clean the enclosure. The humidity rate can be extremely high and is recommended for situations where that is desired.
Search TFO for "enclosures" and/or "sealed chambers" for some great proven ideas! Buy an inexpensive hygrometer(humidity gauge)/thermometer combo, try keeping the substrate moister, and escalate from there.
