I've already read How to switch between the Primary Menus programmatically? but it doesn't actually answer the question. The accepted answer is just two workarounds but not an actual answer to the question.
When my theme is activated, I create several menus and I would like to mark one of them as the Primary Menu.
Is there a wordpress function I can call to make my programmatically created menu the Primary Menu? I'm an experienced developer, but I'm new to wordpress and the terminology in the functions makes it very hard to search the codex to find what I'm looking for. Any help is appreciated.