RAMPS 1.4 with Nema 17: Help

I was using Nema 14 on my last build and I had the steppers running smooth. I just switched to a new build and carried over the same programing on a new Ramps, with Nema 17 motors now. The Z-Axis works fine, however the x and y axis motors were not moving but sometimes they move very fast and shake and rattle.

I have tried:
1) Tuning the potientiometer on top of the Driver. (This made the motor buzz more or less and at one point move crazy)
2) Adjust the x-acceleration, x-vmax, x-jerk to lower settings
3) I have tried switching the stepper motor pairs red-green-yellow-blue

I have no idea what else to try or how to adjust voltage?

I also have no idea what the jumpers do under the drivers. I installed all of them but if anyone has a brief discription of what they do that would help also. Thanks!

[reprap.org]

Short version: they control microstepping, and you want that.

Thanks grat. That link explained a lot. Still can not get the Nema 17's to work right

Your current may need to be turned up by adjusting the pots on the drivers, as well as you may need to lower the max speed. You can compute the Vref voltage for your drivers based on the sense resistor and the rating for your steppers from their data sheet. Check the wiki page for your drivers for details on how to do this. Also start off with a very low speed and work your way faster until you reach a point where it starts locking up and skipping steps, then back it off a little.

Okay, thanks i will try this!