I am creating a wind symphony score and want it transposed when I print. It is very chromatic and I do not want to display any key signatures. I have selected "Hide Key Signature and Show Accidentals In Score Manager, Instrument List. This works great except for the final section we land solidly in a key and I want to display the key signature. 

Anyone do this before? I am looking for a specific answer and not some things to try (thanks in advance). 

Always Show Key Signature In Measure Attributes does not work.