Retain custom sort order when adding a new value to a custom field

I’m talking about creating fields for transactions. For example I have created a benefit received field. Within that field I have “pick one text.” Whenever I add a value to choose from it changes the custom sort I have saved to a default sort. Why would it automatically go back to a default sort every time I add a value? Is there a way to make it not sort by default each time I add a value to pick from?