Single Staff Key Signature with Transposition issue

How can I force an A clarinet part where the orchestra key is A-flat Major into B Major? The default transposed key for the A clarinet is C-flat major. In most scores the clarinets will instead be written in B Major. How do I make this change when no existing key signature will force this change?

Note that I CAN make a similar change in the case of a Bb (B-flat) clarinet. For example, orchestra is in B major, Bb clarinet would default to C-sharp Major, but in most cases the part would be written as D-flat Major. I CAN do this by selecting C-flat Major as local key for the Bb clarinet line, which would then display the desired D-flat Major signature.

The problem with the A clarinet example is that the is no "G-sharp Major" key to select which would display as the desired B-Major. Nor do I find a way to just specify the exact key signature to use on a transposed instrument. Am I missing something? can this be done?

Thank you for any help. MuseScore is a great program.