which sentence is correct:"If i were to decide"or"if i would have to decide"

Question

Answer

I was wrong,i meant:"if i had to decide"

Answer

They have different meanings in the US.
The second means "If I were required to decide"

Answer

In the UK, only the first is correct.

You may hear the second in informal speech in some parts of the USA however, I have been told by an American teacher on Italki, that she would teach only the first option as correct.

Look up grammar on the second conditional.