Computer on Wheels.
I think that a lot of "preceptors" are given the job d/t some arbitrary length of time in the job, not their ability to teach or precept (I mean that for both new grad and not new grad preceptors). I have met RNs with 30 yrs experience who are a wealth of knowledge, but they are horrible for a new grad and don't really have the ability to share that knowledge with new grads. They are wonderful as resource/ charge, for RNs with experience that just have questions about an unfamiliar situation, but it's a different type of teaching.
As far as learning charting in the classroom, I'm 34, so I'm very familiar with doing things on a computer, but I will admit that I never had email until I went away to college at 18, and when I changed jobs and had to learn a whole new learning charting system, it took me several weeks to really get into the swing of things. I knew how to be a m/s nurse, but their charting system, CPOE and flow of things was very new to me. I'm really sorry that you're dealing with such an a$$hat. I just hope it's not a sign of the culture on that floor. Everyone has strengths, and everyone has weaknesses. Some will be better at the computer than others, but telling you to change your assessment findings (something which I'm sure you have very well honed from HH), is pure a$$hattery!