Let’s say I have a trend identified and the market violates a basic trend line drawn in, I find a lot of people say the trend has changed when this happen, but other people do not agree. Can someone assist ?

Maybe I can give you some clarity to this regard. I trade the Currency markets, where trends change quite often in a day. It is best to follow some basics which I learnt from www.forextraderuk.com stating: When a trend line has been violated the market can change direction or it can, merely consolidate. It is therefore important to wait for a confirmation of this violation in the form of a lower/higher high and the market moving to a new high/low point before saying, the trend has now changed.
E.g: Let’s say you have a Bull trend identified and the market violates the trend line support. One has to now see lower highs and lows in place before saying a new bearish trend is in play.