My company uses an old ESR version of Firefox, which of course doesn't suit my needs. So I installed portable FF alongside this one, and uses it almost anytime (I know that I break the company policies...) Up to FF 66, everything was fine, and I only had to launch Portable FF first to have it "taking the lead" and been used by default everywhere. Firefox 67 has introduced the "side by side" feature, which is certainly nice and suits the huge majority of people. But not me... I now have both versions always running alongside, and Windows defaults to the old version, of course, since it is my company's setting. Documentation for FF67 states "side by side mode is now enabled *by default*". Therefore, I have the obvious question: how can I disable this, since it is apparently the default, and not a mandatory setting. I haven't found any clue to do that after many researches....