Thanks so much for your help with this especially the user guide link, will read thru that. There are no buttons anywhere we can find however will definitely look again as it seems mad to me not to have any. The cable I have connecting screen to unit is DVI from back of unit into HDMI on screen This one
https://www.argos.co.uk/product/8587075
As for the monitor.... I found both of these numbers as product number on the box 1CA83AA. and this... 1CA83AA#ABB. so now unsure....the one we have doesn't have the column of buttons on the back and the connections on it are hidden on the back and pointing downwards so you have to tip the screen to see them and to insert the leads!
There is a disc that comes with it but if screen not working I won't be able to see it and if I return I don't want to have used the disc. Jeez wish the OH hadn't got it now... Confused dot com me # beam me up scotty !! Xx