Click the
Change It button, which will bring up a standard Open
dialog. Navigate to the new templates folder, so that you see the name
of the new folder in the popup menu at the top of the dialog.
Click the
Select button at the bottom of the window, and the change will be made. The
Templates menu will be rebuilt, using the templates in the new folder.
Checking Your Change
If you get to experimenting with different folders, you may become uncertain about exactly which folder you've settled on.
In that case, you can select
Show Templates Folder in Finder in the
Files menu, and the folder containing your folder will be opened in the finder with your templates folder selected.