Mold isn't a big allergy problem indoors unless spores (mold's version of seeds) can find a damp spot to grow. Then, look out: Almost any damp spot will do. That includes wood, carpet, paper, and insulation.
Clean up mold where it grows and fix the cause of the moisture, such as a leaky pipe. To keep indoor humidity low, vent bathrooms and dryers, use a dehumidifier, and run vent fans when you cook, clean, and wash dishes.