Mine used to go in predictable order by who's most powerful. I have it set on show power in the heroes tab. And it usually matches up in the enchanting tab. Then I can use the arrows. It's been a bit random lately, but with the mass debut of new heroes on s10 in the space of a few weeks, it's a bit wonky. Also maybe from another ill timed cap raise, I've got o1, started on o2, got cap raise, a few o3. Chaos seems to have ensued.