headstrong
Very stubborn and determined to do things only your own way.
Headstrong means stubbornly determined to do things your own way, even when others advise against it. A headstrong person charges ahead with their own ideas and resists guidance, sometimes to their own detriment.
Picture a student who insists on using a complicated method to solve math problems, refusing to listen when the teacher explains a simpler approach. Or imagine someone who won't ask for directions even when hopelessly lost, absolutely certain they can figure it out themselves. That's being headstrong: confident to the point of stubbornness.
The word contains an interesting image: your head (where you make decisions) is so strong and set that it won't bend or turn, even when it should. Being headstrong is different from being confident or independent. Confident people believe in themselves but stay open to good advice. Headstrong people lock onto their own ideas and won't budge, sometimes missing better solutions or ignoring real dangers.
You might call a horse headstrong when it refuses to follow commands, determined to go in its own direction. The same quality appears in people who value their own judgment so highly that they tune out everyone else. While determination and independence are admirable traits, headstrong behavior often means letting stubbornness overpower good sense.