I actually figured this out shortly after posting...
Go to: wp-admin/includes/post.php
Scroll down to line number 513
You are looking for a block like this:
if ( 'pending' === $q['post_status'] ) {
$order = 'ASC';
$orderby = 'modified';
} elseif ( 'draft' === $q['post_status'] ) {
$order = 'DESC';
$orderby = 'modified';
} else {
$order = 'DESC';
$orderby = 'date';
}
In the final else {} Change:
$order = 'ASC';
to:
$order = 'DESC';
That's it! When you are done the block should look like this:
if ( 'pending' === $q['post_status'] ) {
$order = 'ASC';
$orderby = 'modified';
} elseif ( 'draft' === $q['post_status'] ) {
$order = 'DESC';
$orderby = 'modified';
} else {
$order = 'DESC'; /* used to be ASC */
$orderby = 'date';
}