If you're talking about the properties of of centerline created by annotation tool, then there will be no property highlighted. BTW what changes you're looking to do with that centerline.
As Deepak said, there is not a PropertyManager for centerlines. However, you can change the color, line style, etc. of centerlines with the Line Format toolbar, and you can click and drag the blue boxes at the end of the centerline to change the length. Does this help?
Thankyou for reply.
Actually my concern is when i was dragging the centerline blue box its not incresing its length (This problem is happen with one particular file which is done by others)