How to not snap at someone who is unintentionally annoying
They are old. They are a guest here and want to be helpful, but it ends up being annoying because every time you set down a used pan or cooking utensil, they want to wash it for you. (They know perfectly well we have a dishwasher and that we use it.) They hover while you're working in the kitchen and always seem to be in the way.
It's like they're hijacking my attention span all the time to make decisions. It also feels like (again definitely unintentionally) they're telling you to hurry up and do this thing they want you to do.
I have just come withing a microsecond of biting off their head. I'm baking a pastry, and came to check on it to see where it was at and make sure it wasn't browning too much. I checked internal temperature, noted browning, and the moment I closed the door, before I could turn around to get the foil, they asked me if I knew it was getting brown (that's the way they worded it, "do I know". Fortunately, "YES NO EFFING KIDDING I WAS HERE TO CHECK ON EXACTLY THAT" came out as "Yes."
I don't want to react like this. Please give me pointers.
Have you considered giving them a task to do? Perhaps they feel they should be doing something to help you (for whatever back reason) and this is how they are attempting to feel useful. Give them a specific task and be grateful, then the rest of the time tell them to go relax, or listen to old aunt Gertrude’s stories so she feels listened to. It might get them out of your hair, and allow them to feel they have done something.
Your mileage may vary.
Well, we do give them tasks, but often those don't take much time - there just isn't that much for them to do. I think they are somewhat bored and the dishwashing offers are part of that. I'm very bad at delegating and I should try to do it more and get better at it.
A big thing for elderly is the uselessness, yeah... Is there a longer duration, easy task they can do? Write or type family recipes? Knit gifts (you'd love a pair of warm socks, right? So would your partner!)
Basically something productive and helpful to do that doesn't push your buttons that much.
Perhaps bored and lonely? Half the time it’s a way to try and get more social interaction, especially if they are always in your hair and interrupting you. However, I don’t have a good solution for that, some people just need a lot more general interaction than others.
Can you phrase your needs as a request for personal space rather than any reference to their competence/content of their questions? The more you make it about you and the less about them, the less defensive it's likely to make them. Something like "Sorry, _______, I'm just really used to getting a lot of quiet time while I go about my chores. Do you mind giving me some more space during the day?".
Sometimes direct is the only thing that works.
"I can't have distractions when I'm focusing on cooking so please stay in the other room"
Remind them of this if they set a toe in the room, say a word or start hovering from any distance. Doesn't have to be rude or confrontational, just spell out the problem to them: "you're crowding me / interrupting me".
If it's for a short time that they're staying (a week or less, perhaps), I'd be thinking "Is there really such a huge downside if I just let things get done their way while they're staying?". Sure, it might not be possible with some things, and it might lead to things being a bit different or not quite up to your standards, but if they really want to help I'd be thinking about how to make space for them to do so, even if it means things getting done in a way that might be uncomfortable at first.
I find that I'm quite comfortable relinquishing control and letting things be different to how I'd ideally like them these days, I think because I have worked to actively put myself in situations like that where it's been uncomfortable for me. The more you do it, the more unfamiliar doesn't feel bad (and it can even result in you finding bits that that you want to do their way when they're gone!).
You'd never have guessed it from how I was when I was younger (being a massive perfectionist and generally very particular), though I get a lot of joy from facilitating others' happiness so I do have a natural inclination towards going out of my way to make others comfortable and satisfy their wishes.
Edit: this is just what works for me, I value being a chill and easygoing person and that might not be the right fit for everyone. Furthermore, but far more personal to me:
The other thing I've come to realise is: as a rule of thumb, other people aren't being annoying or doing annoying things, I am getting annoyed by how they are acting or what they are doing. It is not for me to try and control how others act, but I can absolutely examine why I get annoyed and see if some of that comes from me perceiving it in a certain way. 99% of the time people are just doing things with no intent to annoy (though perhaps without considering the impact of their actions), and I can see that as them just being different from me rather than them harming me in any way.