GMAT Strategy

I find it difficult to scroll up and down a RC passage. The MGMAT CAT screen is too small in comparison with the GMATTest Prep screen.

How does the actual screen looks like?
How much do you need to scroll?
Of what length are a short length passage and a long passage?

The scrolling of the paragraph and not having a complete eye span over a passage are two factors to which I can attribute my consistent weak performance in RC. I have been scoring very less in RC: 50% consistently in the last 3 CATs, whereas on paper my accuracy rate and comprehension level is pretty good. Please advice?

Thanking in anticipation
Vikram

The real GMAT looks exactly like GMATPrep.