When I first started to learn to fly in 1998 I had issues with an early ground school test because I couldn’t remember how to convert F to C in temps. Since then I’ve always had my devices (where they had weather) in C. I think I always believed I would move somewhere where I could use it first anyway.
Today I reverted all my devices to F as, well, I realize the dream of going somewhere else is pretty much dead and I do confuse a hell of a lot of people around me with it all.