[rant]
Windows 10 seems to think it's their new, half-baked, Edge browser evidently.  I keep setting it to Adobe Acrobat Reader and it keeps resetting it back to Edge after a little while... 
 
I think it's time to figure out how to uninstall Edge again. 
[/rant]

you have something a miss, pdf have always opened with adobe on all my windows 10 machines without need for constant intervention or uninstalling anything

I set the default back to acrobat a while ago and all has been fine since...

I often get the message that something was wrong and a file association was reset.  This ALWAYS means that a file association I've set to an application I really want to use (say Faststone Maxview for images) gets reset to the program Windows 10 came with (in this case Photo Viewer).  Same thing with music, I want Media Monkey, it resets to it's horrible Groove Music program.
 
I finally did a search and uninstalled most of these new apps that came with Windows 10 (and found I certainly was NOT alone with this issue).  Tonight I disabled Edge - holy crap what a PITA that was!

MS has integrated Edge into Win10 and wants it to replace IE.
 
If you're using wifi, set the connection to metered so windows doesn't make automatic changes or updates. Then set Adobe Reader as default for pdfs. Edge insists on being the default for URL:microsoft-edge and URL:read. I have not been able to disable it and doing so may cause other issues. All other file types go to IE or Chrome and Adobe Reader. Been working without a hitch so far.

I ditched Acrobat a long time ago.  I've had the free version of PDF-XChange Editor for a few months.  Waaaaay better to me.
 
Anyway, there is a setting somewhere that determines whether PDF links get opened in the browser or not.

Go to Settings > Default Apps > Set defaults by app
 
Select Adobe Reader (or whatever) > Choose defaults...  and select all file types there
 
Select Microsoft Edge > Choose defaults...  and deselect everything there

BobF
I ditched Acrobat a long time ago.  I've had the free version of PDF-XChange Editor for a few months.  Waaaaay better to me.
 
Anyway, there is a setting somewhere that determines whether PDF links get opened in the browser or not.

Actually, there was a Chrome update last week which changed that exact setting so I had to fix a few client computers.  It's under the Advanced Settings, in the Content area at the bottom where it says "Open PDF's in the default viewer."  Counter-intuitively, if you check this box, it will try to save the PDF file to disk instead of opening it in Chrome's PDF viewer.
 
Acrobat X and XI no longer work correctly, so I always install Adobe Acrobat Reader DC on client computers (https://get.adobe.com/reader).

 
It happens to me too Craig - every few weeks or so.
 
I reset the default program to Adobe Reader each time but it doesn't seem to stick.
 
 

I have this on one of my Win 10 machines ..to me it seems pretty nice ...not sure if it's what you want .
https://www.foxitsoftware.com/products/pdf-reader/
 
Kenny