Firefox Tekoha Aty

This is a hail Mary. Microsoft changed the behavior of Windows, supposedly for security, so that clicking the Firefox button to make it the default web browser is no longer allowed. Instead, I get taken to the default apps section of Settings, where the only choices are Edge and Internet Explorer. No Firefox. Same with images and with video. Microsoft is not helping with this and I'm damned if I'm wading through probably a hundred or so file extensions changing each one individually. Somebody else must have run across this problem and maybe solved it?

Hi, this AM South Australia time, Firefox did an update again. Later I needed to sign onto Ebay, which required a Capcha verification. After several attempts failed. EBay's solution was to use a different browser. Edge worked fine. What has happened?

Here's one for any techies. For updates (or download). does Firefox for Windows use AppX Deployment Server (dll) directly or via maybe Windows App Installer? I don't understand any of this stuff but the dll is faulty and is destroying every Windows app which foolishly tries to update with it. I beieve it's just done for Windows App Installer among its many scalps I can't system restore, probably due to a dodgy disk drive. I don't want to lose Firefox. Help!