From your post I gather a few things:

1. Problem with RC itself - On this, I think you'll really have to review how you're approaching the questions. My take on RC is always to read for structure, not content. It takes a while to get used to this approach, where you're focusing on the transitions and the organization of the passage to get a feel of what the author is saying. Leave the content out when reading because you can always refer back to the exact details when you answer the question. Sometimes it's also just a matter of getting used to the types of passage they use and the types of questions they ask. It's no secret that with the GMAT, the more practice you have, the quicker you'll become.

2. I'm not familiar with the paper based tests and how similar they are to the current version of the GMAT, if they are even slightly different, you might want to consider just using the OG.

3. Confidence/concentration - For this, the only tip I can offer as it relates to the RC is to take notes on the passage as you read. For me, when I find that I am losing concentration or focus, I begin to just read the words without absorbing anything. But when I force myself to take notes (really short scribbles of the structure/content), then I will pay attention. Doing this might also help overcome your confidence issue as you distract yourself.

Hope this helps. Good luck!