I'm changing a value in the advanced settings of the CMS, specifically the ProviderTypeName of Blogs -> Providers -> OpenAccessDataProvider
However, when rebuilding the site the setting is reverted to its default.
I believe this is happening because the property is stored in a file, and my build and deployment is overwriting it with whatever is in my repository.
Where is this setting stored in the file structure; or if I'm way off base in my assumption, how do I get this setting to stick?
You right, most probably you overrode configuration changes during the deployment. Most of the time, I am excluding all configuration during website deployments and from VS project.
By default, Sitefinity 10 is using a hybrid mode that stores configuration files on both the file system App_Data/Sitefinity/Configurations and the database in table [sf_xml_config_items]. Documentation: https://docs.sitefinity.com/auto-storage-mode-of-configurations
Also, there is a way to move configurations to database only: https://docs.sitefinity.com/database-storage-of-configurations