Windscreen washer jets

[dodsy]

Hi,
New member here and a bit of a novice in regards cars and the Yaris which i really like.

Put my Yaris for MOT today and it passed but i have to fix the washer jets as they are set the wrong way round. So when you try and put the washer jet on for the back window it comes on at the front windscreen instead and vice versa. The windscreen wipers all work ok. I am just wondering how much this will cost approx to fix as i have no idea how to do it myself. I guess its possible that the electric cables are switched round the wrong way possibly to cause it but can it be that simple that the cables just need turned round or will a whole unit need replaced

any ideas anyone? or is it one of these things you dont know till you get it fixed