Matrix question

I have created a matrix question.

I am asking that they rate 6 items on a 1 - 6 scale.

I would like the respondents to only use each number once. In other words give me a priority rating. Is there a setting to achieve this? Or should it not be a matrix?

[jpratt]

This functionality can be achieved by visiting your Matrix item,
Editing your column,
and Selecting Yes for the 'Each answer in this column must be unique' option.