You're Correct!

When facing a shot where the ball is above your feet, you need to make a few changes to your set up in order to successfully play an effective shot.

Initially, because the ball is effectively closer to you than usual, you need to hold lower down on the handle to shorten the length of the club to what is now required. You also need to alter your posture due to the ball being effectively closer to you when it is above your feet, so do not tilt forward as much as you usually would and have less flex in your knees. This will result in you standing up taller than usual but again this is to accommodate the fact that the ball is much closer to you than it usually is.

When you place the golf club next to the ball when it is above your feet, the angle that the shaft creates with the ground has now also altered. If you stand upright and hold your golf club so that it is at waist height and horizontal with the ground, if you look at the club face you will see that it looks like it is aiming to the left (if you are a right handed golfer). So when playing a shot with the ball above your feet, you need to aim the club face and align your body to allow for this. Align your feet more to the right of the target than you usually would and this will allow the club face to aim correctly once again.

You also need to play the ball, regardless of the club that you are using, from the middle of your stance. Due to the slope that you are playing from, your swing will have a more inside to inside swing path than usual. This simply means that the club head will approach the golf ball from the inside of the target line and then swing back on the inside of the target line very quickly, resulting in the club head only travelling directly along the target line for a very short period of time. Positioning the ball in the centre of the feet will allow you to strike it whilst the club head is travelling along the target line, promoting a more accurate result. If you played the ball more forward in your stance, you would strike it whilst the club head was on the inside of the target line, giving you issues with accuracy.

Finally, again due to the slope, you will swing the golf club on a flatter plane than usual. This simply means that the club head will be travelling around you slightly lower than usual and this promotes a shot that will fly right to left in the air, especially with the club face position aiming more to the left as previously discussed. This will result in you striking the golf ball and imparting tilted axis spin on the ball, resulting in the ball flying right to left during its flight. But if you position yourself and align to the right of the target to allow for this ball flight, you will be able to hit an effective and accurate golf shot.

If you do not make any adjustments to you set up when faced with playing a shot where the ball is above your feet, then you will not strike the ball cleanly. You will tend to hit the ground before the ball and as a result the ball will travel forward the distance that is required. If you do manage to strike cleanly, you will now see the ball fly right to left for the reasons mentioned above and the ball will miss the target on the left producing an inaccurate result. Change your set up to retain your strike and accuracy.

Playing the ball above your feet will often make a golfer feel off balance, therefore, a wider stance and not a narrower stance would be preferred. Due to the ball being above your feet, more bend in your knees exaggerates the issue and is therefore not desired either.

Making the golf club longer when the ball is above your feet has a negative effect of encouraging you to hit the floor before the ball. Likewise, tilting more with your spine angle would result in heavy shots and poor contacts.