Content Filtering Policies apply in the order they’re listed in School Manager. Where there is a conflict between policies, the first policy always applies, even if there is another policy below it that does something different.
You can click and hold to drag rules around to reorder them.
Locked policies always appear at the top of the list. Locked policies can be reordered against other locked policies, but not moved below policies that aren’t locked.
We go into policy ordering in more detail in our guide to filtering using categories and signatures.