Windows 10 takes the "wrong" version of vivaldi
I have several version of vivaldi, but win10 still refuse to correctly associate the current version.
I see current version both in settings (metro app) and default programs (legacy way) but when I set as default... nothing happens. It still uses the other version. It happens as well also with "open with".
Ok, for the moment seems to be associated. I only have to remove older versions from file associations to prevent possible windows hijackings
@Hadden89: that's completely weird - but it doesn't surprise me with Win10, which generally makes a dog's breakfast of the default app architecture. If I were you, I'd make sure all "non-default" versions of Vivaldi were uninstalled, but first that I had an offline installer for each of them. Then I would designate and test the one I wanted as default, ensure that Windows knew and believed this, and then re-install the non-default ones. See if that sticks.
Obviously, you can also work it "backwards" by ensuring each relevant filetype was set to open with the Vivaldi install that you want it to, by working from the filetype to the handler rather than the other way around. I have had to do that in the past. ATM, Win10 is respecting my default app assignments, so I can't really test your problem. PLUS, if you have the same version installed in multiple locations, I could promise nothing. But these are my ideas.
Fiddling in the registry I see the various vivaldi associations per file type/vivaldi builds, however if it works fine now I won't touch anything