Selection of an arc

[beginner]

I'm writing drill for the first time and stumbling my way through it. I've created a couple sets, and got stuck! Here is my problem: I created an arc, and from that arc, am splitting it into two halves. The first half was fine and I was able to create a straight line with that group. The second group (still in the form of an arc), when selecting the group, the system automatically thinks I want the ends of the arc to switch places completely. In order to select the whole group, I have to manually do it (lasso tool) or else it thinks the 2 performers on the end should either be excluded, or only selected by themselves.
How do I have the entire group selected, and when a straight line is formed, the end points don't switch positions, but instead, remain the ends of the straight lines?
Thank you!
Gina