My Africn Violets appear to have a fungus growing on the soil and pot kinda yellowish brown any help with this?

If you have been watering from the bottom as you should there may be a built up of salts on the soil, Run water through top and flush salts away.....If that isn't the case .....make a solution of tobacco and water.....(strip paper and filter off cigarette butts) soak tobacco in water and pour onto plant surfaces.....Rosie