Reverse order of dropdown list from input box

Which dropdown are you referring to and where?

In the text box before the dropdown select box for Items, only the item code can be typed. The dropdown will show the item name only and will be prefixed with the item code only if the "Show Item Codes" checkbox is ticked in the Preferences menu. Where do you get/see "symbols"?

If however, in Setup => Company Setup, the Search Items checkbox is ticked, then the textbox besfore the Items dropdown can be searched by Item Name when by Ajax, the dropdown will get filtered.

As mentioned, the new version of FA sorts items in a different order. I realized it may have something to do with the new version of mysql or php.
The sql concerned is

SELECT stock_id, s.description, c.description, s.inactive, s.editable
            FROM 0_stock_master as s,0_stock_category as c 
            WHERE s.category_id=c.category_id   ORDER BY c.description,stock_id;

which is found in include/ui/ui_lists.inc: function stock_items_list()

I tested adding REGEXP '^[a-z]' DESC, an answer I found in stackechange, and it works. But I cant figure out where the ORDER BY is located. It is not in the ui_list.php. Can someone point it out for me?

The ORDER BY is implemented in the array_merge() array's element of the first argument and remains the same in both FA 2.3.x and 2.4.x as:

'order' => array('c.description','stock_id')

What did you change it to, in order to make it the way you wanted?