You're Correct!

If you are looking to play your longest golf shots then you need to hold the golf club at its full extent. The higher up the grip you hold, the longer the distance is between your shoulders and the golf club head.

The longer the distance between your shoulders and the golf club head, the wider you will swing the club head around you and you will create a bigger swing arc around you. The bigger the swing arc is, the more distance the club head has to travel around you and as a result of this, the more time you have to pick speed up with the club head. The more speed you swing the club head with, the more speed is transferred to the ball during impact and as a result, the further you will hit your golf shot.

If you look at the grip on the golf clubs handle, you will see that it has a colored line around it, close to the butt end of the grip. If you are not sure how far up the handle to hold, hold so that this colored line sits just outside your upper hand. This will be your left hand if you are a right handed golfer. Ensure that all of your left hand is on the grip and if the colored line is close to the join of your hand and wrist, you are holding the club at its full extent.

When you place your left hand on the grip, try the following to ensure you locate it on the handle correctly. Point the fingers on your left hand (for right handed golfers) directly down at the ground. Now place the handle of the golf club diagonally across your hand from the middle joint of your index finger to the callous pad just below your little finger. Ensure that you do this about inches down from the top of the grip. Now close your fingers around the back of the handle and wrap your hand around the front. This should now result in all of your left hand being below the colored line around the end of the grip.

If you hold at the bottom of the grip, you are shortening the length between your shoulders and the club head. The shorter this distance, the smaller the swing arc that the club head will travel around you and as a result of this, you will not hit the golf ball as far.

If you hold so that your upper hand hangs over the end of the golf club, you will not have a good hold on the club and as you swing the club around you, you will find it more difficult to keep control.

If you vary how far up and down the grip you hold the club, then you will experience a variation in how far you strike the golf ball. This will make distance control with your golf shots very difficult. Ensure that you hold in a consistent position on the grip so that you know the length of shot that the position creates.