Board templates can be saved in order to make future board creation even more efficient. If you would like to learn more about saving boards as templates, check out this article.
Make adjustments to saved templates utilizing the following steps:
Open the board you originally saved as the template board. You can do this by searching the board/template name from your dashboard or going to FILE>OPEN from any board you're currently on.
Once on the template board, make any adjustments desired.
That's it! The next time you go to launch a new board and select that template, all of your changes will be reflected.