Hello Bob Thanks for posting on the Lucidchart Community! You can change the text size and alignment of text within a shape from the toolbar at the top of the editor. To make it a default for that shape you can add the shape (after setting the desired text size and alignment) to a custom shape library. When you drag that shape out from that custom shape library after that it will maintain that text size and alignment.

Below is a gif in which I adjust the text size and alignment and then add it to a custom shape library so that the new shape from that custom library matches the desired text size and alignment.

If anyone else has questions about adjusting text please check out our Work with Text article. For information about creating and managing custom shape libraries please check out our Shape Libraries article.