I’m not experienced by any means, but from all the reading I’ve done, I can tell you to look for vents on your unit. Look in your unit’s instruction booklet, or online if you don’t have them, and find where they’re located, and open them all the way. It’s harder to lower humidity than raise it. If you’re home is humid, it’s not gonna get much lower than the ambient humidity. Also, if you have any hatched chicks in there, that will raise it...expect that. Don’t remove the chicks though.
With the vents open, your temp control unit should compensate. What is the humidity reading?