If you want to zoom in for detail and still see further ahead, most radars have the ability to offset your own ship's position on the screen.
If your ship's position is offset, the bearing scale is no longer useful. For example, the orange electronic bearing line (EBL) is 90 degrees from your bow, but points to 120°.
As you zoom in or out, the pulse length will most likely change automatically. Many radars let you change the pulse length manually.
Short pulse is good when you zoom in and want good sepration between targets. Long pulse for long distances, but objects close together may blend into one target.