How do I tell which details actually matter at work?

You give the same intensity to the trivial and the significant, so a small irritation gets the energy that a real problem deserves. The trouble is you are sorting by what bothers you rather than by what matters, and those are not the same thing. Some things annoy you loudly while changing nothing, and some quiet things decide everything. The skill you are missing is not caring less. It is caring proportionally. Ask of each detail: if this were wrong, what would actually happen? Most things, honestly answered, turn out not to move the outcome at all. A few genuinely do. Learning to feel that difference — to let the small things be small — is most of what focus really is. Try a simple filter this week. Before you pour effort into fixing something, ask whether it changes the result or just scratches an itch. If it only scratches the itch, let it go, on purpose. You will find you have far more attention for the things that count when you stop spending it on the things that merely nag.