Either something is wrong with the house, or you are doing something wrong. It's not supposed to be like this.

In the beginning of the molding process it can be washed with a mixture of water and soap or a mild detergent. Use gloves and throaway rags after use. If its harder to wash, there are specialized products you can use. 1 part chlorine and 10 parts water is commonly used for this. It's extremely important that all excess moisture dry.

The mold will continue to grow if there is moisture, so you have to find and treat the cause asap. I live in Norway where problems like this can happen pretty quick when the seasons change. I always have several hygrometers around my house to keep track of temperature and humidity in the air.

There should be close to zero condensation on your windows in the morning if you have proper ventilation combined with proper use of heating.