Hi Miquel,
As it's a cross tab, when you select one column, it will select all the columns, because you're not really selecting one column (you're selecting an object values, Valores). So, you need to update the formula/condition in the Conditional formatting window as below (in both the places in the Formatting Rule Editor window, you attached in the snapshot)
=(Last([Per_Head]) < [Media Per_Head]) and ([Valores] = 12) (in formula on top to highlight rows in red)
=(Last([Per_Head]) >= [Media Per_Head]) and ([Valores] = 12) (in formula at the bottom to highlight rows in green)
Let me know if that helps.
Thanks,
Mahboob Mohammed