Creating a template doesn't change anything on its own — you assign it to the characters, entities, or places that should use it. There are two ways to do this.
One at a time, from the object
On a Character, Entity, or Place edit form, find the Profile Template dropdown and pick your template. You must save the object with the template selected before it takes effect — choosing it in the dropdown alone won't apply it until you save.
In bulk, from Mass Assign
To assign a template to many objects at once, click the orange "Mass Assign Templates" button at the top of the Profile Templates page. The Mass Assign screen has three tabs: Player Characters, NPCs, and Entities.
On any tab, choose a template from the dropdown, tick the objects you want to assign it to (the Toggle All checkbox selects the whole list), then click "Update All Selected". Each tab is saved on its own, so update Player Characters, NPCs, and Entities separately.
Places aren't part of the Mass Assign tool — assign a template to a place from its own edit form using the dropdown described above.