if something is right to me then why is that it is wrong to others?
Because "right" and "wrong" are subjective and need to be debated then agreed to. There is no universal objective "right" or "wrong". Some will try to claim that there is but there is not. Others will try to claim that their god dictates what is "right" and what is "wrong" and if you don't believe in their god, you still are subject to what they are claiming to be right or wrong anyways.
I have my own personal way of determining what is right and wrong for me.
Here is my way of reasoning.
If the act injures or causes unnecessary harm to another person it is wrong.
If the act helps or aids another who may be in harm or injured it is right.
If the act injures or causes unnecessary harm to oneself it is wrong. (questionable)
If the act helps or aids oneself from preventing harm or injury it is right.
If the act damages or destroys property that does not belong to you personally it is wrong.
If the act protects or secures the property that don't belong to you personally it is right.
The third aspect can be questionable for example consuming drugs is not necessarily bad but when they are abused they can be harmful. There is always a point when an activity can become harmful but recreational use is rarely ever harmful.
There are of course other examples of how things could potentially be harmful such as dangerous sports which if done safely don't actually cause harm unless the safety measures fail. This is where I bring in the aspect that if it is one's own doing with full acknowledgement of the potential for harm then it is not wrong to partake in the activity.