How do I write a piece in a minor key?

I know this sounds like a dumb question, but I am stumped.

Each Key Signature represents both a Major and it's relative Minor. I am working on C#minor, of which the relative major is E. 4 sharps in the key signature. I also want Solfege movable Do on the notes.

If I add the the key signature and then the notes, when I enter the notes I get C# = La instead of C# = Do.
If I add the notes prior to adding the key signature, I get I get C# = Do as it should. But then when I add the key signature it switches to La as would be correct for E major. See attached clips.

I tried changing "Key signature mode" to minor in the inspector for the key signature element, but it goes right back to unknown when I click in the score to return to editing.

Any suggestions greatly appreciated.

Steven Wheeler