The fungicide SHOULD kill most of the fungus. so rince the roots etc & repot. You may have fungal knats which are hard to eliminate.... removing the old soil will help but adults/larva may be living in other areas (floor) of the room so watch for them

Mold on top of the soil is usually the result of being kept too wet. Fungas gnats are also from too moist conditions. Gnats can be controlled with BT. Probably the most readily available source of BT is the mosquito dunks used to kill mosquito larvae. Disolve dunk in water and sprinkle water on soil. It is non toxic and will not hurt your plants. Be sure your plants are getting enough air circulation. Maybe a small fan in the room would help. Al