I heard about that too. But as in many times in Islam, different scholars have different opinions.For Arabs, the use of the right hand for greeting has less to do with religion than with the fact that they use the left hand to wipe themselves after sitting on the toilet. To greet someone with the left hand is to symbolically give them s--t.
One is "It doesn't matter"
Right is preferd
And even its not allowed to wear it on the left. (I don't find the source anymore)
As I mentioned in older posts. Sometimes you just are a couple of friends and suddenly wear it all right.