Aiyah don't worry lah, my friend's son was exactly like this at 21 months, her paed told her this age is very normal one, their brain developing faster than their self-control. Someone in my mum WhatsApp group mentioned that at this age they don't really "disobey," they just literally cannot stop themselves yet, so scolding doesn't work well. My neighbour tried the positive discipline approach, get down to eye level, short simple words, redirect instead of just saying "no", and she said within a few weeks her boy much better already.