virtualbox.org

I'm running VBox 5.0 26 on a Win7 host and have lately been having trouble with recent Windows 10 Insider Builds as guests.
I've asked the VBox control panel if there are any updates available and it responds that I'm on the latest version.
But VBox has reportedly released 5.1 and I wonder why I'm not being advised of its availability.

I feel I must be missing something important but I don't know what it might be.

Why doesn't VBox consider 5.1 a more "current" version than 5.0 26?

The developers are holding back on "baptizing" an update stable through that mechanism until they are confident enough that the update won't cause more problems than it will solve.

Also, check your settings in the VirtualBox Manager Preferences, Update. Maybe you have selected the "Stable Release Versions" instead of "All New Releases" or even "All New Releases and Pre-Releases". And check the update frequency as well...