Okay, Two parts to this issue.... 1: Part One - Snagit Plugin Autoscroll Helper - the reason I need an older version of Firefox available 2: Part Two - Part one will only work if Part Tow can be retained on older version. I use a plugin tool called SNAGIT autoscoll helper by TechSmith (or rather used to). The latest Firefox does not support one of the it's primary features, this stopped working approx 2 years ago and Mozilla have disabled it being installed on current versions . TechSmith are just as disengaged and do nothing to resolve or provide an alternative for MAC on any browser. I thought if I could install two versions of Firefox the latest plus a legacy version (so I can simply autoscoll web page capture), I MAY be able to somehow limp through life in this less that okay way. Technically the following suggestion works. https://www.haykranen.nl/2011/08/04/howto-run-multiple-versions-of-firefox-side-by-side-on-mac-os-x-lion/ BUT (the big BUT)...even though I download version v50.0 (which allows the plugin) and set to 'not' autoupdate. I get everything running, as soon as I close the older version of Firefox and relaunch it does what it likes and updates this old version to v57.0...this is so not cool! How do I prevent this and how can I get multiple versions functioning? I have left messages on TechSmiths site as well but as the two seems to be blaming each other for the disconnect...maybe someone in the community has a work around? Ideas greatly appreciated....and Mozilla if there is 'anything' you can do to get the plugin reinstated and integrated with your latest version, that would be fantastic! Thanks