Post type archives are ordered by date, descending by default. This isn’t always desirable, especially for content whose chronology isn’t important.
There are a few recommended methods for changing the order of custom post type archives, but the best technique I’ve found is this one:
This example specifically changes the custom post type archive order to order by post_title ascending, but it should be pretty easy for you to figure out how to order by another property and direction.
I have found that this technique is more robust and reliable than using the pre_get_posts hook.