I need to set a default app for the extension
.rels in Windows 10. However, the “Choose default apps by file type” does not list that extension.
I went to a file of that type in the file explorer and right clicked and could set the app there. But that still doesn't put it in the “Choose default apps by file type” and I need it there for WinZip to use that association.
Where—and how—can I add an extension?