Cannot change 1st secondary rune.

Whenever I'm trying to mix my runes up and tweak them for the match ahead of me, the secondary rune set is buggy. You click on the first secondary rune spot, it changes the second secondary rune and leaves the first as is. You click the second secondary rune and it changes the second secondary rune, leaving the first as it is. Basically, there's no way to change the first rune of the back set without wiping the back set entirely and starting over.