If there are marks being left on the material from the pinch rollers. You can tighten the pinch roller screws on the back of the cutter to raise the pinch rollers to apply less pressure.
The gold thumb screws are what you would want to adjust, it would be best to mark the screws where you can know how many turns you have done so that both screws are turned the same amount. You will want to test them after each adjustment. (You want to be sure to adjust with the rollers in the up position. Where they are not touching the vinyl.) By testing, you will feed the vinyl through and back to make sure the vinyl isn't shifting. Once you have it feeding through correctly and it isn't leaving deep marks in your vinyl you are done.