In order to apply new changes from the template sheet to the current file, you need to delete the embedded reference. To do that, open the schematic editor and follow:
- File > Schematic Settings... > Schematic Data > Embedded Files
- There you should see an embedded file reference, select and delete it and then close the window.
- Now go to the File > Page Settings.. again
- From the Drawing Sheet section select the template file you modified and click OK
Now the changes should be applied to the page.