No, there is no way to "retrieve" the old version. But re-installing a previous version is possible, but there are pitfalls depending on a few things. Plus if the computer remains connected to the internet. when opening Firefox the first time with out creating a special file before hand and also having that file in the correct folder, Firefox will just update to the latest version as you watch on the "first launch". Any further information requires more info from you, mainly exactly which previous version the "robust" one was. Wrong guess and you may end up with a can of worms, as far as your Firefox user data is concerned. IMO, you are better off letting one of us help correct what you think is wrong with the "brand new one". I suspect that your got the usual monthly update that has a few minor changes and maybe an "issue" that is easily fixed by you with out help and guidance.