apple watch
will the apple watch 7 have watch os 8 after a factory reset even though the previous owner had watch os 9?
Question marked as
No it won't. Once it has been updated to WatchOS9, it will remain on WatchOS9 and there is no path backward. I'm guessing you can't pair the watch with your iPhone because you don't have at least an iPhone 8 or newer? Restoring the watch to factory isn't going to solve this for you. You need a newer iPhone.