HCA: Hermit Crab Association

So I'm a new crab owner, have a 10g with 2 crabs, both currently seem to be molting.
One above surface which has been stressful but anyways.

Was looking for ideas on how to decorate my crabitat, also ways to increase humidity. Saran Wrap was working for a while but for some reason I can't get it above 75.

Do you have the grate type lid? Also is there a fan around them? I have a fan in my room and if it ever gets turned on my tank drops to 70% humidity

I have the ac on but it hasn't decreased the temp. I took 2 sponges out cause I don't want bacteria to create and I just bought moss today hoping that helps.
I have a mesh lid

There's an article on how to calibrate a hygrometer in the care guide section. A lot of the time the gauges are either off or broken, even when they are brand new. It's never a good idea to panic about humidity until you are sure there is a problem!!