Behavior policies are used in filters "by reference." A change to a behavior policy definition changes that definition in every filter that uses (references) the behavior policy.
If the behavior policy is being used by any published policies, you will be asked if you want to update devices in the field immediately. Because behavior policies are shared across policies, make sure you know what policies any behavior policy will affect.
Find the behavior policy in the list that you want to edit, and then click the corresponding View button in the right column. (The buttons in the right column appear when you hover the mouse pointer over the row.)
Changes immediately affect any policy that uses the behavior policy.