Somehow my party leader changed to my second character, who has the lowest charm and poorest speaking skills in the party. I would like to switch it back to the first character who has these skills. According to the keyboard commands chart, Ctrl + F1 should change my party leader to character 1. However Ctrl + F1 brings up some kind of keyboard binding program and I can't make heads or tails of it. How do I make my first character the party leader again?

Go to their profile screen (the one with the buttons to access inventory, etc, and the listing of all their stats on the right). Click on the bar at the top, which says "not leader" and the character should become the leader. Note that if you do this during an event (talking to someone, fighting, etc) they seem to only become leader for that event. Personally I prefer to have my "combat leader" (ie the person with high perception) as the leader by default, as you generally don't get advanced warning about perception checks. When I'm doing something social, I'll then switch leadership to my charismatic character for that encounter.

and clicking within paper doll window/part of char info screen as well changes leadership to that char.