This happens to me way more often than it should.

resting depressed face

Gosh, yes, it's annoying. I'd be constantly getting people telling me to cheer up. Once a lady on the bus to school gave me a looooong pep talk about how I'm so pretty and if anyone picks on me it's because they're jealous, and I was like, whaaa? I can only assume I looked really sad, but I was probably just thinking about a video game or Formula 1 😅

As I got older, my resting sad face turned to resting angry face. 🤷🏽‍♀️

Also I have to say, strangers telling you to cheer up can just eff right off, especially when they follow it up with "it's not that bad". They can naff right off with that, how presumptive to think they know what's going on in my life.

What is hard is when someone asks me a question that requires a decent amount of thought. I can either maintain my face or think. I can't do both.
- When I have to do something with my hands that requires dexterity, but it's impossible to see with my eyes, I close my eyes, slightly open my mouth, and bare my teeth. I can feel myself doing it.
  I've wondered what people think of me when I'm making that face- need to ask my coworkers.
If someone tells my wife to smile more she has perfected the most psychotic looking grin to give in return. Wish I could do that. I usually scowl even harder.

I get asked, "What's wrong?" all the time. Or, "Are you angry/mad/concerned/intense?"

Meanwhile, it's 3 stooges and keystone cops in my brain 24/7.

My ADHD makes me forget social norms.

Sometimes I'll smile at a funeral or look mad at a party. I also have been known to say something totally inappropriate for the social context.

Also my resting face tends to be disgusted

"Your face doesn't match how you say you feel"

Even though I come from a rather stiff culture - feels. My normal face is angry face and my slightly disappointed face is apparently a totally pissed off face.

The hardest part for me is figuring out when to smile. It is weird if you go around smiling but it is also weird if you never smile.
- I really like a cognitive behavioral therapy technique for this. If I remember, on my way to work, I'll put on a relaxed smile. Literally think happy thoughts. I believe it's helped me to naturally smile more. I definitely see the effect when meeting and talking with strangers, which I have to do often. It's either that or I'm just getting better at it naturally.