That's happening on my dad's new laptop as well - he still uses his MS Office 2013 license because why not, but even after many attempts we couldn't figure out a way to make Windows open double-clicked files in that old Office. It would always pop up the newest unactivated test version. And before that it took a while until the OS even listed the programs in the start menu. MS literally fights its own software when you don't pay the annual 365 ransom.