If it's by the heel, the clubs are too upright. Run the test a few times to ensure an accurate reading. If your swing is consistent, the marks should overlap. If the test proves your clubs need adjusting, take them to a pro for a proper bend. The same is true of your clubs, except this rubber is in the form of the grip.
Grips are also available in leather and various synthetics, and with a wide choice of patterns.
Each model has a different feel, so you can alter the feel of your clubs by switching grips. Remove the old grip by carefully slitting it lengthwise and peeling it away. Then, depending on your replacement grip, you typically apply a liquid solvent to the sticky-taped butt end of the shaft, slide the new grip on, align it, and let it sit for a day. Some new grips don't require solvent. Golf shops sell regripping kits that come with all the necessary parts and instructions.