finicky
Very picky and hard to please about small details.
Finicky means extremely particular and hard to please, especially about small details. A finicky eater might refuse perfectly good food because the peas are touching the mashed potatoes, or because their sandwich was cut into rectangles instead of triangles. A finicky cat might turn up its nose at dinner unless the food is exactly the right temperature and served in the right bowl.
When something mechanical is finicky, it only works under very specific conditions. An old printer might be finicky, jamming unless you load the paper just right and press the buttons in exactly the correct order. A finicky lock might stick unless you jiggle the key at precisely the right angle.
The word suggests that someone or something is fussy beyond what seems reasonable. While it's fine to have preferences, a finicky person focuses so much on tiny details that they make simple things unnecessarily complicated. Being finicky about keeping your desk organized might be helpful, but being finicky about how your friends tie their shoelaces would be exhausting for everyone.
Today, calling someone finicky usually carries a gentle criticism: it suggests they're making life harder than it needs to be.