Worth mentioning - but the size of the 'arc' the wiper sweeps across is not adjustable.
However, it may be that the wiper arms are not set correctly (ie the arms are fitted incorrectly onto the spindles that protrude from the trim panel below the screen). With the wipers turned off and parked at the bottom of the screen, there are a small black marker dots on the glass (they have a ring of clear glass around them and are in the black section at the bottom of the screen) that far end ends of the wiper should line up with and just sit on. Also, the driver's side blade should sit parallel to the bonnet. If it is fitted too 'high' up the screen to start with, then it will sweep past the side edge of the screen at the top end of the sweep. This starting/parking position can be altered by loosening the nut securing the wiper spindle, pulling the arm off the 'splines' of the spindle, refitting further round and retightening the nut.
Pete