Korean has different politeness levels and honorifics that confuse me?

Korean politeness can feel overwhelming, but day to day you mainly need two registers. Use the polite -요 ending (haeyo-che) with most people — strangers, shopkeepers, colleagues, anyone older — and the formal -습니다 style for very formal settings, presentations, or customers; save casual 반말 only for close friends your age or younger who've okayed it. The single most important rule is to default to polite forms with anyone older, senior, or newly met, and add -님 to titles; people are very forgiving of grammar mistakes from foreigners, but using 반말 with the wrong person is what actually feels rude. When unsure, just stay on -요 and you'll almost never offend anyone.