What combination of OS X, Endnote, Word just WORKS?

Keep in mind that with the EndNote X8 installed in Word 2016, there will be no EndNote sub-menu option under Tools and there is no floating toolbar. If you have a new or existing document open and the Word document is wide enough, you would see the EndNote tab in the ribbon as you see in this image.

My goodness, there it is!   Sorry, it never occurred to me that the Endnote tools would not be in the accustomed place … 

So: we have established that:

in a ‘clean’ account running under High Sierra 10.13.3 on my new MacBook Pro 2018, which I created at my first startup (as opposed to an account migrated later from my old MacBook Pro 2011 running Yosemite, that may have imported or created problems by some unknown means), it is possible to start running Endnote X 8.2 with Word 2011 and Word 2016.  They both seem to work equally well, at least initially.  (I say ‘initially’, since I must bear in mind the earlier post by dtoub, who in this thread and elsewhere has flagged up an issue of Endnote X 8.2 starting to run slowly after having been in use for some time.)

I appreciate that I could move over all my work to the ‘clean’ account, and simply abandon the migrated account.  But I am reluctant to do that because of the difficultly of moving a large number of settings, passwords, etc.   I therefore intend to follow the advice of Apple advisors referred to earlier, ‘nuke’ the SDD on my new MacBook Pro 2018, and remigrate from the old machine, in the hope that there will be no glitches this time.  

Then I shall want to install Endnote X 8.2, which will of course have been nuked with all the rest, and hopefully everything will then work like a dream (at least for a while, pace dtoub!).

So, my final query (for a while, I hope) is this:

How to I arrange to redownload and reinstall  my purchase of Endnote X 8.2, when I have nuked it and all the other stuff on this computer, given that I have paid for it?  What details shall I need to provide in order to have the right to do this?

You can find the EndNote installer download here:

https://support.clarivate.com/Endnote/s/article/EndNote-Installer-download

You will need your Product Key to complete the installation:

https://support.clarivate.com/Endnote/s/article/EndNote-Locate-your-serial-number-or-product-key

Word 15.38 (i.e. Word 2016 for Mac) and EN 7.7 & 7.8 work just fine. I did have problems with later versions of Word and EN 7.7, so beware!

After a lot of work (which I won’t go into in detail), I would like to report that I now have Endnote 8.2 and Word for Mac 2011 working together on OS X 10.13.3 High Sierra on my new MacBook Pro 2018.

In essence, I had to conduct a remigration (via Time Machine) from my old machine onto a clean reinstall of OS X in a way that ensured that there were no permissions problems.   (Hours and hours online all evening and into in the small hours of the morning with Apple senior advisors to get there.)  Then I resintalled Endnote 8.2, and so far (about 48 hours later) I do not seem to have any problem.

Thanks to Jason and all others who have posted helpfully and patiently on this thread!

Ok