Audacity 3.6.3 - offline manual

Hi, folks.

I’ve been asked to install Audacity 3 instead of the old 32 bit Audacity 2 used for years.

I’ve downloaded the ZIP for Audacity 3.6.3 64 bit.
I’ve downloaded the offline manual file so that I have {audacityfolder}\help\manual\index.html

When I launch Audacity, and click help/manual, it takes me to the online version.

I’ve tried copying the lot to C:\Program Files\Audacity (so I have Audacity exe plus the help\manual folder in that Audacity folder.

The manual suggests that I can force it to use the internet manual by changing an option in Preferences/Interface - that doesn’t show.

Using Sysinternal’s ProcessMonitor, it doesn’t look like it’s searching for anything in “help” or “manual” folder (or anything .html) either when the software launches, or when I select help/manual.

Am I missing something really obvious?