Yeah I remember when BA first introduced it there were a few problems. I just ask the passengers to use the arm rest controls instead, the screen can be controlled by using the directional arrows and enter button. If you dont have success asking the nobby behind you then just ask one of the crew descretly, we are good at sorting things like that out...especially with kids!
The thing that bugs me is that the touch screen is rather sensitive and doesnt respond well to being constantly banged by the person using it, generally it only needs a light touch to get what you want. If it needs a firm pressing of the screen then it usually just means the screen needs cleaning and the crew have access to alcoholic wipes for this!