How to rebuild Launch Services Database in Sierra?

Unfortunately John that is part of the problem. The file downloadable from the bank is a Quicken file which (don't have Quicken) my digital checkbook program called Moneydance uses to import transactions. After right-clicking on the downloaded file, using the "Open With" and thinking I could check dates using TextEdit prior to importing into MoneyDance this file AND ALL FILES DOWNLOADED FROM MY BANK whether chosen as Excel, Quickbooks, csv, etc. are downloaded as TextEdit files. The Get Info/Open With option does not include Excel, Numbers or any other application that makes sense. It offers Adobe Illustrator, Calibre, Evernote, Quicktime Player, Safari Script Editor, Send to Kindle and Textmate as the options. Excel or Numbers won't open the file. The file downloads as:

QFX_1_0_2?x-csrf=6dMg6q8qRE2KOIgXfmg-Ug2

Using my laptop to download the file yields the correct file which is:

I'm now wondering if this is not a Launch Services rebuild database issue to correct this, but something else.

John, just checking, when I triple click your string there are a couple of spaces (maybe 1) after the end. Should that be there? Check where the cursor falls after the -v, I get:

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchSe rvices.framework/Versions/A/Support/lsregister -kill -r -domain u -domain s -domain l -v

well I took the plunge and ran the script in Terminal as it was copied. Saw a bunch of code being executed so I hope this worked and did no damage. I always take a very deep breath when opening Terminal. I will now restart and try downloading again.

just to report back, after restarting I tried to download the QFX file again and it is still identified as a TextEdit file. Where oh where is the ability to unlock that unfortunate Get Info pane "Open with" setting? This is ridiculous, I've done the exact thing before but never had it lock in like this (1-2 OS updates prior). This has got to be a bug. I'm hoping I won't have to take the nuclear option and do a complete erase and clean install from Time Machine prior to this event.

While it successfully adds the correct icon to the file, it is unable to be opened by any application that normally would open it - Excel, Numbers, Moneydance. Assigning the extension unfortunately does not actually change the file type - or appear to anyway.

Unfortunately all freshly downloadable files (whether chosen as Excel, QuickBooks, Quicken or csv are ALL downloaded as this stupid file type. None of those applications will open the files and of course Moneydance won't either. Since the file is freshly downloaded each time (using Safari) and comes in as a TextEdit file I do agree that the OS is doing something to alter the file to something only TextEdit can read. I've been downloading these files correctly for years, and it does download correctly on my laptop where my unfortunately choice of "Open With" was not done.

I've just received information to try to run your Terminal code string with sudo in the front. What are your thoughts? Here's the comment:

I can tell you for a fact that the terminal command you tried running DOES need sudo. Running it without sudo is useless. Try it again but with sudo at the front.

It can't be the browser because Safari successfully downloads it on my laptop. Unfortunately Safe Mode did not work - same file is downloaded in Safe Mode. Any other troubleshooting possibilities before I go nuclear and restore from Time Machine?

Hmm. no Eau Rouge, I didn't. I just ran the code John gave, will try downloading after restarting to see the effect. Then I'll do that in Onyx.