Between Farmwithjunk and Soundguy you'll get the right advice on how to set up a plow. I'd suggest trying some of the advice Farmwithjunk gave and then post back with more questions.
One thing about the sway chains. Though I trust Farmwithjunk's advice, I think you should still have the chains, but adjust them loosely so as to prevent the 3 pt. hitch from swaying so far the implement bumps the tires.
No one suggested removing the sway chains. At least not me.... But a plow needs to be able to drift side to side and NOT be tied solid with chains or stabilizer bars. Otherwise, the plow will be in control of the steering of the tractor. (Rather than front wheels/operator)
Some tractors will have sway chains that limit draft arms from hitting tires, and SEPARATE stabilizer bars/chains. Others utilize the sway chains (in an adjustable form) as stabilizers. It's helpful to differentiate which type in a discussion like this... Regardless of type, a plow needs to have freedom to move side to side, independent of the tractor. In a case where sway chain serve the dual function of sway chains AND stabilizers, they need to be adjusted to the point where the draft arms are just barely clearing the tires. With tractors employing sway chains and separate stabilizer bars/chains, the stabilizer bars stay in the barn when the plow is attached to the tractor. THERE is where the confusion might have arisen.
Also, keep in mind we're talking exclusively about 3-point mounted plows. With a semi-mounted plow or a trailer type, none of the above applies.....
Making a plow trail correctly is STRICTLY a function of proper adjustment of the plow. Anything other than that and you'll have a fight on your hands in regards to controlling direction of the tractor AND plow. With a plow mounted rigid to the tractor, even the slightest correction in direction will become exaggerated and hard to control.
The track width of the tractor needs to be set correctly. With MOST compacts, that turns into a series of compromise's, due to what is normally a much more narrow track width and the common use of wider tires than was "customary" with tractors built "in the day" when plowing was a primary consideration in tractor design. (R4's can be a real killer....) Adjust tractor to fit the plow rather than plow to fit the tractor..... THEN the plow adjustments come along to make the plows line of draft follow centered behind the tractor....It's really simple, but can be somewhat of a "black art"....Get everything set accordingly, and the plow will trail almost effortlessly.
