What trick do you WISH you could teach your cat?

My old cat, when something was wrong with her world, she'd come and meow at me - she had a special "fix this!" meow - and then she'd lead me over to whatever was wrong: I'd like the litterbox cleaned, I want fresh water, I want the window open, top up my food please. Sometimes I couldn't fix it (rain, snow, dietary restrictions), but she'd accept it if I couldn't change it.
The new cat just screams for things to be fixed, but there's never any indication as to what's wrong. Plus she has serious chronic health conditions, so sometimes it's I'd like fresh water please and other times the exact same meow means we have to go to the 24-hour emergency vet right now. Which is really much less helpful and informative than I'd like it to be. Also, if it's something I can't fix, she just decides that I haven't understood and keeps meowing.
- Ah shit, sorry to hear that bud

Had a cat that was able to fetch. It was so cute and he always made such a proud face when he brought back the object I threw. I miss him so much.
- Taught my gf’s cat to do that, my own doesn’t most of the time though which is very disappointing

Use the toilet and remember to flush
- Pick 1
  
  Only knowing how to flush sounds really annoying. Knowing cats they would just start flushing over and over again when they are bored.
- Easily done.
  To teach the shitting part you'll need a spare toilet seat. Take that seat and screw it into a toilet box and place it next to the toilet. Every few weeks raise the spare seat up by a few inches until it's next to the toilet. Then remove the spare seat and box.
  To teach how to flush, react with treats every time the cat hits the flusher. Be prepared for all night flushing.

To remember that we've spent almost 18 years together and that we're best friends. That we've carried each other and comforted each other through so much.
There was that time I had to climb fifty feet up a tree with hardly any limbs with ropes and a harness to get him when the crows goaded him into climbing higher. The rusty antique farm equipment below would have mangled him had he fallen. I had to lift him with one hand, balanced, hoping he would roll out of my grip, and put him in a cinch top bag with a rope attached to lower him to my wife on the ground. Once he reached her hands, I broke down and sobbed while I made my way to them. I was so scared. I woke up the next day and he was curled up around my hand, holding tightly. He didn't want to go outside for months.
He pees on me regularly now. Sometimes when I come home with my hands full and can't give him attention immediately. Sometimes when I've been home all day and he didn't get a snack fast enough. Maybe his kitten baby sister is trying to play with him or he's stuck on the other side of the door while I'm brushing my teeth. He has hyperthyroidism and kidney disease. We give him everything, do the best we can for his health care, but it's getting close to the time we say goodbye and it's breaking my heart.
I just wish he'd remember me the way I remember him.
I lifted him onto my lap yesterday morning, out of the reach of his gentle but playful six month old kitten sister. He peed all down the front of me. I didn't scold; I just held him until he was done, knowing the last time I hold him isn't far away.
- I can't read this tonite, you already got me teary

To rob a bank and make a clean getaway.
- Doesn't PussInBoots already do that?

How to wipe her ass on toilet paper when poop gets stuck to it instead of the goddamn carpet!

My cat did that, with nerf gun bullets. But she insists that she taught me to throw the toys, rather than me teaching her to fetch.
- I mean, thats fair, u on the wrong side or this issue 😂

Stop meowing at night after I’m asleep.
- How come they don't join you when its bedtime?
  
  They do. Then after I fall asleep, they start walking around the house and yowling.

Shitting in the toilet

Instead of marking his territory by pissing on things, I'd prefer if he wrote his name on a post-it note.
- I wish you well in this endeavor

I wish Izzy could stop eating when she's full. If you put too much food down for her at once, she'll eat it all and throw it up. She has to be fed by the teaspoonful about ten times a day or my world will be turned to cat vomit. "Ability to stop eating when full" would be a nice trick.
- Screw that, get her a puzzle feeder with all the grooves like an ice-cube tray or something else that makes her "think"/"work" for it. I used to have a scarfer/gulper too but its slows her right the fuck down 😹
  How about no/zero throwups lol
  
  She'd scream herself to death while I was loading it.
- You can get timed cat food dispensers.
  
  Doesn't help with her wet food. We have to feed that to her half a can at a time.

Well, to clean himself but now he does that and it’s rare he needs cleaning. He always cleans his paw before leaving the litter box on its walls so that’s not fixed.
Maybe to play on his own or chill if I dont want to play. If I work he somehow never bothers me, aside for the occasional “meow let’s play” moment here and there. But when I play games, or read, he just goes “hi motherfucker” and start meowing all the time and when he sees that meowing fails he decides that the best course of action is to jump on my television; it’s a 4k euro tv so you can imagine how funny it is, more so now that he scratched it a lot
So my choice goes to “stop fucking scratching my television”
- Do you have another cat or is it him all by himself?
  
  Just him

I wish I could get her to understand that sometimes doors need to be closed. She hates a closed door, be it the front door or the door to the bathroom or balcony, regardless of whether anyone is on the other side of the door or whether she herself cares at all about the other side of the door.
She can also open doors, so we have to bolt the front door. Our bathroom doesn’t have a lock though, so we’re just waiting for an awkward incident there.
- Same struggle, the other cats know to look to the other one as the resident little bandit, such little shits lol
  In what world is the hierarchy NOT supposed to be
  Door > Cat
  ?
  Edit: its honestly not that bad aha. They're generally pretty respectful, but they know to stay away during #2. That's a hard ljne I had to draw
  
  My cat is far too smart for me, which should be embarrassing, but she’s very smart. She once broke a glass bottle (with water in it, so no smells) on a tile floor, then pulled a bath mat over the shards so she didn’t hurt herself. But she also straight up hides things for fun sometimes.
- Can I ask about the most important situations where you NEED this to be the case? Like pick your battles but when do you need to take up that battle aha?
  
  Basically just the front door and the bathroom door, though we pee and shower with the door open, as long as nobody’s visiting. We’ve got a storage room that we’d like to not have to heat, but we can’t keep the door shut lol

One of my friends in Finland has a couple of cats, one is fairly disinterested in people but the other loves to play fetch with her toys. It's ridiculously cute.
- God im jealous
  
  I'd say to be careful what you wish for, because once the game has begun, it doesn't end until the cat is bored. It's impossible to resist the cute drop / sad little cat-activation-noise when you get distracted and don't notice.

One of my cats plays fetch I wish the other did too but he’s a slouch.
- I've heard its a double edged sword. Tbh, my cats are bad enough that i literally can't just like drop or toss anything without them carrying out a full-blown no-warrant drug-sniffing-cats criminal investigation so its probably just as well

To stop scratching my damn furniture.
- Set up scratch posts next to or on your furniture.
  
  We have done everything. He’s still intent on ripping up carpet and shredding sofas.

I'd love to teach my cat to fetch as well. She does the first half of fetching where it'll run after whatever you throw, but then doesn't bring it back so you have to go and pick up the toy to throw again.