I think you have to edit “C:\Users\%username%\…\Sidefx\houdini18.0\houdini.env” Check if there is such a line , if not, add it, and edit it, such as : HOME = “C:\Users\yourpath\Sidefx”
This may be worth articulating for others: The Windows HOMEvariable dictates where Houdini will set HOUDINI_USER_DIR.
Some applications set a HOMEvariable explicitly, so Houdini produces a different HOUDINI_USER_DIRresolution when loading from that environment.
Since some of us use applications like Cmder or VS Code, which *add* a HOMEvariable to the windows default environment, Houdini's default launcher will also set HOUDINI_USER_DIRto that location. Not ideal, if you're making a Houdini plugin.
To summarize: Houdini will determine HOUDINI_USER_DIRbased on HOME.. To find out where that goes, type set HOMEin a windows terminal you plan to launch from.
@SideFX: From a tool authoring perspective, this behavior seems fragile; maybe it's worth creating another environment variable which stabilizes the location?