Choose Low and it has little influence on how you match. Choose High and the system will look for a very high level of agreement in your matches. In other words, it tells the system you do not want to match with anyone who has not filled out the exact same profile. For instance, if you're seeking a new partner for tennis doubles, you wouldn't want to match with anyone who didn't fill out the Tennis profile. You'll notice that all the questions in a profile are on a gray background.
Most questions have two columns of answers, one on the left and one on the right.
When you see the round Radio Buttons in a column, it means you can only make one choice from the items in that column. If you choose another item in that column, the radio button you clicked first becomes unchecked. When you see square Check Boxes in a column, it means you can make as many choices in that column as you please. All the checks you click into the boxes will remain there. The more answers you choose on this side, the more people you'll match with.