You shouldn't have ever needed to go into Preferences?
And you don't need to type every {author} and {author_sort} -- just the ones that are different from the default calculation:
FN, LN <--> LN, FN
If you want to use all {authors} as {author_sort}, without recalculating, go to Preferences ==> Advanced ==> Tweaks
And check out the Tweak for "Author sort name algorithm".
It has a "copy" option which uses the FN LN {authors} value as-is.