Adjusting global playback pitch

Hello!

I have a friend with perfect pitch, but over the course of her life her perfect pitch has shifted. It's very disorienting and troubling for her, especially as she composes music; when she gets an idea in her head and goes to write it down, it all sounds wrong to her. This is a natural phenomenon for elderly people with perfect pitch, and for people who have facial surgeries and the like. Right now when a C is played, she hears a C#, though that will likely continue to change somewhat.

She was wondering if it's possible to adjust the global playback pitch of Musescore to accommodate her changing ears. She'd like to set it so that when she writes a C, it plays back as a B (so that she continues to hear a C). It seems that her ears are off just about a semitone exactly, so any feature designed for baroque tuning (aka A=415) would work, but something more flexible that can help as her ears shift further would be ideal.

Thanks for your help!