When I start Obsidian it opens in the Help vault which was the one I selected as an initial vault on installation. However, I’d like to have it open my regular vault, but I can’t see where to set that as a default
There’s no “default” vault. Instead, Obsidian opens the vault that was last open when the app was quit. If you close the Help vault and leave your main vault open, that’ll be the one that opens.
There was a feature request about that from someone who claimed this wasn’t the behaviour at all. (I responded the same as @ryanjamurphy did there).
Think that request can be closed then because it’s not a real request.