Mould in apartment

Because of the temperature differences between the street and the apartment, there is a high humidity in the room, the livingroom and the bathroom, so I found extremly big black mould smudges under the windows, around the windows, in the corners under the windows area, behind the toilet, behind the bed on the wall, close to the floor, and specially in the bedroom, behind the bed on the floor after few days I found moisture condensation.