Module downloaded but does not appear in Vassal list

I downloaded module Bussaco. Win 10 Home with Edge. Vassal 3.2.17
It was in Downloads folder and I moved it to my Vassal Games folder.
Double clicked and it opened.
Entered Name and Password. It ran.
It is not in the Vassal list.
Experiments with other modules resulted in that when downloaded they have to be run from the Downloads folder before being moved to appear in the Vassal list.
I have Deleted Bussaco from all folders and downloaded it again and double clicked from download folder. It opens but does not ask
for Name and Password and is still not in the list.
I have been into preferences and removed name and password, no success.
I presume somewhere Vassal stores a list of all modules that it displays but I cannot find it.
Can anyone help me please so that I can have this module in my Vassal list.
Thank you.

On Windows, VASSAL stores preferences in a hidden folder-- C:\Users*username-here*\AppData\Roaming\VASSAL\prefs

It sounds like your global VASSAL preferences might be corrupted (this file is in the above folder and is named V_Global). I’d try deleting it, whereupon it will be recreated next time you launch VASSAL.

I would also recommend that instead of opening modules by double-clicking them and allowing VASSAL to handle it, work the other way around–launch VASSAL first, then File menu → Open module. In a normal scenario there is no reason why you can’t store modules in a variety of places, and there’s certainly nothing special about the Downloads folder that requires you to run them from there first before moving them where you ultimately want to keep them.

Thank you for your quick response. I never would have found the list without your help.
Problem solved.
Thank you.