How to decide whether to pick 4-bromo-2-methoxyphenol or 4-bromo-6-methoxyphenol as the name for the compound? Why is the following compound named as 4-bromo-2-methoxyphenol and not 4-bromo-6-methoxyphenol? 
Shouldn't the substituents be numbered according to their alphabetical order?
When choosing which name to use when the only difference is the numbering, we choose the combination that gives the lowest possible numbers, 2 and 4 in this case.
So the name will be 4-bromo-2-methoxyphenol. The substituents are given in alphabetical order.