Hide key signatures in transposing instruments

How can I hide the key signature of transposing instruments? While horns and trumpets have an option when selecting the instrument for the player (a “No Key Sig” variant), this does not seem to be possible with clarinets (and probably others that I do not have on my radar at the moment).

Hiding key signatures in Notation options does not work either.

One can set the score to “Atonal” to eliminate key signatures in all instruments, something Philip Rothman at NYC Music Services recommended to me when I recently (sort of recently) sent him a theater score of mine for printing and any comments he might make.

Granted my score had lots of modulations in it. Added to that, he cautioned to make sure each score/part stated whether it was Transposed or Concert pitch.

@Derrek Thank you for that tip! Quite logical, actually! I could bite my a** if I reached it…

But then I would really like to know, why there are special entries for Horns and Trumpets? Those, that come with “No KeySig”? Any idea, why they are there? (There is probably also an easy explanation for them, so I better gonna order a self-a**-biter from Amazon right now…)

In the 19th century it was standard to write brass instruments with no key sig, partly because they often played on instruments pitched differently from the notated transposition(s) anyway. This has carried over for “classical” players even today, especially Horns.