If you are referring to a Dropdown Field from your database then it is sorted based on the field settings. You can edit the field and rearrange it in the order you like then it should be reflected in your form.
If you are referring to a linked record then it is sorted by the 1st Non-Personal View in the table you are linking to.
- For example if table is 'Tasks' and you are linking to 'People' then go to the People table and sort your top most view how you want it to show up in dropdowns.
I always keep the generic view at the top for this reason.
