Yes it will have an effect on arrow flight.

If your arrows are fishtailing they are moving side to side and you need to move your rest either right or left. If they are porpousing then you need to move your nock point up or down on your string.

There are a bunch of other things that could also be the problem like arrow spine, tip weight, string strech, etc... But we will assume that you got that OK.

Go to Eastons web site and download their tuning guide. It will run you through the entire tuning process.