It is not your laptop as I have a brand new Lenovo only a few months old. It is bloody Microsoft and always has been. They are intrusive and crap.
I don’t remember exactly what I did now, but this is one of the pages that helped
https://www.thetechminute.com/set-adobe-reader-default-pdf-viewer-windows-10/
Trust me, it’s a Microsoft thing, and a windows 10 thing, which is one of the reasons I had avoided upgrading the old machine for so long.
BTW, if you use external drives, don’t be surprised if you find encripted locks on them at some point, especially if you buy a new machine, and plug in an old drive from the previous machine. MS loves to lock your files. Upon buying my new machine, I have already discovered at least 50 gigs of files locked and lost, and I have another over 1 tb to look through still. So aggravating.
Plan Your Life In Color!