You could use global variables, or better yet, session variables in these places.
Then by setting the global variable, or session variable once, it would apply to all these settings.
This is true for almost any setting where "quotes" are used. Any of these fields can hold an expression.
Of course using this approach you still have to set the actual template field, but if you wanted to change the contents of the field, that would be very quick to do.
cheers
Bruce