This is one of those things that's a bit silly when it comes to home drip brewers, because it basically confuses everyone. Although I'm not specifically familiar with your machine, here's how these knobs typically think. First, you have to understand the basic rules of brewing coffee in a drip machine. For brewing a full 10 cup pot, the process should take 6 minutes, and the water should come in contact with the beans at 200 degrees F. In order for the brew time to be as needed, a full pot must be brewed. However, many of us will brew smaller pot sizes of 1/3 to 1/2. During brewing, the amount of water needed rushes through the brew cycle too quickly, thus resulting in an underextracted pot of coffee. So, what these little "strength" settings do is allow the water to be distributed to the beans, or pass more slowly, so that the coffee flavor can be properly extracted over a full 6 minutes. And yes, you're correct at any volume, if you want to increase the strength of your coffee you can use more (1-2 T per 6 oz cup is the recommended range).